This application is a continuation of U.S. patent application Ser. No. 11/419,756 filed on May 22, 2006, which is a continuation of U.S. patent application Ser. No. 10/467,961 filed on Dec. 5, 2003, which is a national stage application filed under 35 USC 371 based on PCT/EP02/01820 filed on Feb. 21, 2002, which international application claims priority of German Application Nos. 101 09 021 filed on Feb. 24, 2001, 101 17 803 filed on Apr. 10, 2001, 101 40 345 filed on Aug. 17, 2001, and 102 03 486 filed on Jan. 30, 2002, all of which applications are incorporated herein by reference in their entirties.

The present invention relates to substituted xanthines of general formula

the tautomers, the stereoisomers, the mixtures thereof and the salts thereof, particularly the physiologically acceptable salts thereof with inorganic or organic acids or bases which have valuable pharmacological properties, particularly an inhibiting effect on the activity of the enzyme dipeptidylpeptidase-IV (DPP-IV), the preparation thereof, the use thereof for preventing or treating illnesses or conditions connected with an increased DPP-IV activity or capable of being prevented or alleviated by reducing the DPP-IV activity, particularly type I or type II diabetes mellitus, the pharmaceutical compositions containing a compound of general formula (I) or a physiologically acceptable salt thereof and processes for the preparation thereof.

In the above formula I

R¹denotes a hydrogen atom,

a C_1-8-alkyl group,

a C_3-8-alkenyl group,

a C_3-4-alkenyl group which is substituted by a C_1-2-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkylamino-carbonyl, di-(C_1-3-alkyl)-amino-carbonyl, pyrrolidin-1-ylcarbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl-group,

a C_3-8-alkynyl group,

a C_1-6-alkyl group substituted by a group R_a, wherein

- R_adenotes a C_3-7-cycloalkyl, heteroaryl, cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkylamino-carbonyl, di-(C_1-3-alkyl)-amino-carbonyl, pyrrolidin-1-ylcarbonyl, piperidin-1-ylcarbonyl, morpholin-4-ylcarbonyl, piperazin-1-ylcarbonyl, 4-methylpiperazin-1-ylcarbonyl or 4-ethylpiperazin-1-ylcarbonyl group,

a C_1-6-alkyl group substituted by a phenyl group, wherein the phenyl ring is substituted by the groups R¹⁰to R¹⁴and

- R¹⁰denotes a hydrogen atom,
- a fluorine, chlorine, bromine or iodine atom,
- a C_1-4-alkyl, hydroxy, or C_1-4-alkyloxy group,
  - a nitro, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)amino, cyano-C_1-3-alkylamino, [N-(cyano-C_1-3-alkyl)-Nâ€”C_1-3-alkyl-amino], C_1-3-alkyloxy-carbonyl-C_1-3-alkylamino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl or 4-(C_1-3-alkyl)-piperazin-1-yl group,
- a C_1-3-alkyl-carbonylamino, arylcarbonylamino, aryl-C_1-3-alkyl-carbonylamino,
- C_1-3-alkyloxy-carbonylamino, aminocarbonylamino, C_1-3-alkyl-aminocarbonyl-amino, di-(C_1-3-alkyl)aminocarbonylamino, pyrrolidin-1-yl-carbonylamino, piperidin-1-yl-carbonylamino, morpholin-4-yl-carbonylamino, piperazin-1-yl-carbonylamino or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonylamino, C_1-3-alkyl-sulphonylamino, bis-(C_1-3-alkylsulphonyl)-amino, aminosulphonylamino, C_1-3-alkylamino-sulphonylamino, di-(C_1-3-alkyl)amino-sulphonylamino, pyrrolidin-1-yl-sulphonylamino, piperidin-1-yl-sulphonylamino, morpholin-4-yl-sulphonylamino, piperazin-1-yl-sulphonylamino or 4-(C_1-3-alkyl)-piperazin-1-yl-sulphonylamino, (C_1-3-alkylamino)thiocarbonylamino, (C_1-3-alkyloxy-carbonylamino)carbonylamino, arylsulphonylamino or aryl-C_1-3-alkyl-sulphonylamino group,
- an Nâ€”(C_1-3-alkyl)-C_1-3-alkyl-carbonylamino, Nâ€”(C_1-3-alkyl)-arylcarbonylamino, Nâ€”(C_1-3-alkyl)-aryl-C_1-3-alkyl-carbonylamino, Nâ€”(C_1-3-alkyl)-C_1-3-alkyloxy-carbonyl-amino, N-(aminocarbonyl)-C_1-3-alkylamino, Nâ€”(C_1-3-alkyl-aminocarbonyl)-C_1-3-alkylamino, N-[di-(C_1-3-alkyl)aminocarbonyl]-C_1-3-alkylamino, Nâ€”(C_1-3-alkyl)-C_1-3-alkyl-sulphonylamino, Nâ€”(C_1-3-alkyl)-arylsulphonylamino or Nâ€”(C_1-3-alkyl)-aryl-C_1-3-alkyl-sulphonylamino group,
- a 2-oxo-imidazolidin-1-yl, 2,4-dioxo-imidazolidin-1-yl, 2,5-dioxo-imidazolidin-1-yl or 2-oxo-hexahydropyrimidin-1-yl group wherein the nitrogen atom in the 3 position in each case may be substituted by a methyl or ethyl group,
- a cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkyl-aminocarbonyl, di-(C_1-3-alkyl)-aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl, morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonyl group,
- a C_1-3-alkyl-carbonyl or an arylcarbonyl group, a carboxy-C_1-3-alkyl, C_1-3-alkyloxy-carbonyl-C_1-3-alkyl, cyano-C_1-3-alkyl, aminocarbonyl-C_1-3-alkyl, C_1-3-alkyl-aminocarbonyl-C_1-3-alkyl, di-(C_1-3-alkyl)-aminocarbonyl-C_1-3-alkyl, pyrrolidin-1-yl-carbonyl-C_1-3-alkyl, piperidin-1-yl-carbonyl-C_1-3-alkyl, morpholin-4-yl-carbonyl-C_1-3-alkyl, piperazin-1-yl-carbonyl-C_1-3-alkyl or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonyl-C_1-3-alkyl group,
- a carboxy-C_1-3-alkyloxy, C_1-3-alkyloxy-carbonyl-C_1-3-alkyloxy, cyano-C_1-3-alkyloxy, aminocarbonyl-C_1-3-alkyloxy, C_1-3-alkyl-aminocarbonyl-C_1-3-alkyloxy, di-(C_1-3-alkyl-aminocarbonyl-C_1-3-alkyloxy, pyrrolidin-1-yl-carbonyl-C_1-3-alkyl-oxy, piperidin-1-yl-carbonyl-C_1-3-alkyloxy, morpholin-4-yl-carbonyl-C_1-3-alkyl-oxy, piperazin-1-yl-carbonyl-C_1-3-alkyloxy or 4-(C_1-3-alkyl-piperazin-1-yl-carbonyl-C_1-3-alkyloxy group,
- a hydroxy-C_1-3-alkyl, C_1-3-alkyloxy-C_1-3-alkyl, amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl, di-(C_1-3-alkyl)-amino-C_1-3-alkyl, pyrrolidin-1-yl-C_1-3-alkyl, piperidin-1-yl-C_1-3-alkyl, morpholin-4-yl-C_1-3-alkyl, piperazin-1-yl-C_1-3-alkyl, 4-(C_1-3-alkyl)-piperazin-1-yl-C_1-3-alkyl group,
- a hydroxy-C_1-3-alkyloxy, C_1-3-alkyloxy-C_1-3-alkyloxy, C_1-3-alkylsulphanyl-C_1-3-alkyloxy, C_1-3-alkylsulphinyl-C_1-3-alkyloxy, C_1-3-alkylsulphonyl-C_1-3-alkyloxy, amino-C_1-3-alkyloxy, C_1-3-alkylamino-C_1-3-alkyloxy, di-(C_1-3-alkyl)-amino-C_1-3-alkyloxy, pyrrolidin-1-yl-C_1-3-alkyloxy, piperidin-1-yl-C_1-3-alkyloxy, morpholin-4-yl-C_1-3-alkyloxy, piperazin-1-yl-C_1-3-alkyloxy, 4-(C_1-3-alkyl)-piperazin-1-yl-C_1-3-alkyloxy group,
- a mercapto, C_1-3-alkylsulphanyl, C_1-3-alkysulphinyl, C_1-3-alkylsulphonyl, C_1-3-alkylsulphonyloxy, arylsulphonyloxy, trifluoromethylsulphanyl, trifluoromethylsulphinyl or trifluoromethylsulphonyl group,
- a sulpho, aminosulphonyl, C_1-3-alkyl-aminosulphonyl, di-(C_1-3-alkyl)-amino-sulphonyl, pyrrolidin-1-yl-sulphonyl, piperidin-1-yl-sulphonyl, morpholin-4-yl-sulphonyl, piperazin-1-yl-sulphonyl or 4-(C_1-3-alkyl)-piperazin-1-yl-sulphonyl group,
- a methyl or methoxy group substituted by 1 to 3 fluorine atoms,
- an ethyl or ethoxy group substituted by 1 to 5 fluorine atoms,
- a C_2-4-alkenyl or C_2-4-alkynyl group,
- a C_3-4-alkenyloxy or C_3-4-alkynyloxy group,
- a C_3-6-cycloalkyl or C_3-6-cycloalkyloxy group,
- a C_3-6-cycloalkyl-C_1-3-alkyl or C_3-6-cycloalkyl-C_1-3-alkyloxy group or
- an aryl, aryloxy, aryl-C_1-3-alkyl or aryl-C_1-3-alkyloxy group,
  - R¹¹and R¹², which may be identical or different, each denote a hydrogen atom, a fluorine, chlorine, bromine or iodine atom, a C_1-3-alkyl, trifluoromethyl, hydroxy or C_1-3-alkyloxy group or a cyano group, or
  - R¹¹together with R¹², if they are bound to adjacent carbon atoms, also denote a methylenedioxy, difluoromethylenedioxy or a straight-chain C_3-5-alkylene group,
  - and
  - R¹³and R¹⁴, which may be identical or different, each denote a hydrogen atom, a fluorine, chlorine or bromine atom, a trifluoromethyl, C_1-3-alkyl or C_1-3-alkyloxy group,
- a phenyl-C_1-4-alkyl group wherein the alkyl moiety is substituted by a cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkyl-aminocarbonyl, di-(C_1-3-alkyl)-aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl, morpholin-4-yl-carbonyl group and the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl group substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-C_2-3-alkenyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-(CH₂)_m-A-(CH₂)_n-group wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined and

- A denotes a carbonyl, cyanoiminomethylene, hydroxyiminomethylene or C_1-3-alkyloxyiminomethylene group, m denotes the number 0, 1 or 2 and n denotes the number 1, 2 or 3,

a phenylcarbonylmethyl group wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined and the methyl moiety is substituted by a C_1-3-alkyl group,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, m and n are as hereinbefore defined and

- B denotes a methylene group which is substituted by a hydroxy, C_1-3-alkyloxy, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, mercapto, C_1-3-alkylsulphanyl, C_1-3-alkylsulphinyl or C_1-3-alkylsulphonyl group and is optionally additionally substituted by a methyl or ethyl group,
- a naphthyl-C_1-3-alkyl group wherein the naphthyl moiety is substituted by the groups

R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a naphthyl-(CH₂)_m-A-(CH₂)_ngroup wherein the naphthyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, A, m and n are as hereinbefore defined,

a naphthyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the naphthyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, B, m and n are as hereinbefore defined,

a [1,4]naphthoquinon-2-yl, chromen-4-on-3-yl, 1-oxoindan-2-yl, 1,3-dioxoindan-2-yl- or 2,3-dihydro-3-oxo-benzofuran-2-yl group

a heteroaryl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

a C_1-6-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

an R²¹-A-(CH₂), group wherein R²¹denotes a C_1-3-alkyloxycarbonyl, aminocarbonyl, C_1-3-alkylaminocarbonyl, di-(C_1-3-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl or morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl, 4-methylpiperazin-1-yl-carbonyl or 4-ethylpiperazin-1-yl-carbonyl group and A and n are as hereinbefore defined,

a phenyl-(CH₂)_m-D-C_1-3-alkyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴and m are as hereinbefore defined and D denotes an oxygen or sulphur atom, an imino, C_1-3-alkylimino, sulphinyl or sulphonyl group,

a naphthyl-(CH₂)_m-D-C_1-3-alkyl group wherein the naphthyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, D and m are as hereinbefore defined,

a C_2-6-alkyl group substituted by a group R_b, wherein

- R_bis isolated by at least two carbon atoms from the cyclic nitrogen atom in the 1 position of the xanthine skeleton and

R_bdenotes a hydroxy, C_1-3-alkyloxy, mercapto, C_1-3-alkylsulphanyl, C_1-3-alkylsulphinyl, C_1-3-alkylsulphonyl, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl or 4-(C_1-3-alkyl)-piperazin-1-yl group,

a C_3-6-cycloalkyl group,

or an amino or arylcarbonylamino group,

R²denotes a hydrogen atom,

a C_1-8-alkyl group,

a C_2-6-alkenyl group,

a C_3-6-alkynyl group,

a C_1-6-alkyl group substituted by a group R_a, wherein R_ais as hereinbefore defined,

a tetrahydrofuran-3-yl, tetrahydropyran-3-yl, tetrahydropyran-4-yl, tetrahydrofuranyl-C_1-3-alkyl or tetrahydropyranyl-C_1-3-alkyl group,

a C_1-6-alkyl group substituted by a phenyl group, wherein the phenyl ring is substituted by the groups R¹⁰to R¹⁴and R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl group substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-C_2-3-alkenyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-(CH₂)_m-A-(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, A, m and n are as hereinbefore defined,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, B, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

a C_1-6-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

an R²¹-A-(CH₂)_ngroup wherein R²¹, A and n are as hereinbefore defined,

a phenyl-(CH₂)_m-D-C_1-3-alkyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, m and D are as hereinbefore defined,

a C_2-6-alkyl group substituted by a group R_b, wherein

- - R_bis isolated by at least two carbon atoms from the cyclic nitrogen atom in the 3 position of the xanthine skeleton and is as hereinbefore defined,

or a C_3-6-cycloalkyl group,

R³denotes a C_1-8-alkyl group,

a C_1-4-alkyl group substituted by the group R_c, wherein

- R_cdenotes a C_3-7-cycloalkyl group optionally substituted by one or two C_1-3-alkyl groups,
- a C_5-7-cycloalkenyl group optionally substituted by one or two C_1-3-alkyl groups,
- an aryl group, or
- a furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrimidyl or pyrazinyl group, wherein the abovementioned heterocyclic groups may each be substituted by one or two C_1-3-alkyl groups or by a fluorine, chlorine, bromine or iodine atom or by a trifluoromethyl, cyano or C_1-3-alkyloxy group,

a C_3-8-alkenyl group,

a C_3-6-alkenyl group substituted by a fluorine, chlorine or bromine atom or a trifluoromethyl group,

a C_3-8-alkynyl group,

an aryl group or

an aryl-C_2-4-alkenyl group,

and

R⁴denotes an azetidin-1-yl or pyrrolidin-1-yl group which is substituted in the 3 position by an R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein

- R_edenotes a hydrogen atom or a C_1-3-alkyl group and
- R_ddenotes a hydrogen atom, a C_1-3-alkyl group, an R_fâ€”C_1-3-alkyl group or an R_gâ€”C_2-3-alkyl group, wherein
  - R_fdenotes a carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkyl-amino-carbonyl, di-(C_1-3-alkyl)-aminocarbonyl, pyrrolidin-1-yl-carbonyl, 2-cyanopyrrolidin-1 -yl-carbonyl, 2-carboxypyrrolidin-1-yl-carbonyl, 2-methoxycarbonylpyrrolidin-1-yl-carbonyl, 2-ethoxycarbonylpyrrolidin-1-yl-carbonyl, 2-aminocarbonylpyrrolidin-1-yl-carbonyl, 4-cyanothiazolidin-3-yl-carbonyl, 4-carboxythiazolidin-3-yl-carbonyl, 4-methoxycarbonylthiazolidin-3-yl-carbonyl, 4-ethoxy-carbonylthiazolidin-3-yl-carbonyl, 4-aminocarbonylthiazolidin-3-yl-carbonyl, piperidin-1-yl-carbonyl, morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl, 4-methyl-piperazin-1-yl-carbonyl or 4-ethyl-piperazin-1-yl-carbonyl group and
- R_g, which is separated by two carbon atoms from the nitrogen atom of the R_eNR_dgroup, denotes a hydroxy, methoxy or ethoxy group,

a piperidin-1-yl or hexahydroazepin-1-yl group which is substituted in the 3 position or in the 4 position by an R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein R_eand R_dare as hereinbefore defined,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted by an aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, (2-cyano-pyrrolidin-1-yl-)carbonyl, thiazolidin-3-yl-carbonyl, (4-cyano-thiazolidin-3-yl)carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety in the 4 position or in the 5 position is additionally substituted by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein the methylene group in the 2 position or in the 6 position is replaced by a carbonyl group,

a piperidin-1-yl or hexahydroazepin-1-yl-group substituted in the 3 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein in each case two hydrogen atoms at the carbon skeleton of the piperidin-1-yl or hexahydroazepin-1-yl-group are replaced by a straight-chain alkylene bridge, this bridge containing 2 to 5 carbon atoms if the two hydrogen atoms are located on the same carbon atom, or 1 to 4 carbon atoms if the hydrogen atoms are located on adjacent carbon atoms, or 1 to 4 carbon atoms, if the hydrogen atoms are located at carbon atoms separated by one atom, or 1 to 3 carbon atoms if the two hydrogen atoms are located at carbon atoms separated by two atoms,

an azetidin-1-yl, pyrrolidin-1-yl, piperidin-1-yl or hexahydroazepin-1-yl group which is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a -(C_1-3-alkyl)amino-C_1-3-alkyl group,

a piperazin-1-yl or [1,4]diazepan-1-yl group optionally substituted at the carbon skeleton by one or two C_1-3-alkyl groups,

a 3-imino-piperazin-1-yl, 3-imino-[1,4]diazepan-1-yl or 5-imino-[1,4]diazepan-1-yl group optionally substituted at the carbon skeleton by one or two C_1-3-alkyl groups,

a [1,4]diazepan-1-yl group optionally substituted by one or two C_1-3-alkyl groups, which is substituted in the 6 position by an amino group,

a C_3-7-cycloalkyl group which is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl group which is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms on the cycloalkyl moiety are separated from one another by at least two carbon atoms,

an Nâ€”(C_3-7-cycloalkyl)-Nâ€”(C_1-3-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms on the cycloalkyl moiety are separated from one another by at least two carbon atoms,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

an Nâ€”(C_3-7-cycloalkyl)-Nâ€”(C_1-3-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

an Nâ€”(C_3-7-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

an Nâ€”(C_3-7-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a C_1-6-alkyl group, a C_3-6-cycloalkyl, C_3-6-cycloalkyl-C_1-3-alkyl, aryl or aryl-C_1-3-alkyl group and
  - R¹⁶denotes an R¹⁷â€”C_2-3-alkyl group, wherein the C_2-3-alkyl moiety is straight-chained and may be substituted by one to four C_1-3-alkyl groups, which may be identical or different, or by an aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, (2-cyano-pyrrolidin-1-yl)carbonyl, thiazolidin-3-yl-carbonyl, (4-cyano-thiazolidin-3-yl)carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group and
  - R¹⁷denotes an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein, if R³denotes a methyl group, R¹â€² cannot represent a di-(C_1-3-alkyl)-amino group,

an amino group substituted by R²⁰, wherein

- R²⁰denotes an azetidin-3-yl, azetidin-2-ylmethyl, azetidin-3-ylmethyl, pyrrolidin-3-yl, pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-3-yl, piperidin-4-yl, piperidin-2-ylmethyl, piperidin-3-ylmethyl or piperidin-4-ylmethyl group, while the groups mentioned for R²⁰may each be substituted by one or two C_1-3-alkyl groups,

an amino group substituted by the groups R¹⁵and R²⁰, wherein

- R¹⁵and R²⁰are as hereinbefore defined, while the groups mentioned for R²⁰may each be substituted by one or two C_1-3-alkyl groups,

an R¹⁹â€”C_3-4-alkyl group wherein the C_3-4-alkyl moiety is straight-chained and may be substituted by the group R¹⁵and may additionally be substituted by one or two C_1-3-alkyl groups, wherein R¹⁵is as hereinbefore defined and R¹⁹denotes an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

a pyrrolidin-3-yl, piperidin-3-yl, piperidin-4-yl, hexahydroazepin-3-yl or hexahydroazepin-4-yl group which is substituted in the 1 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)amino group,

or an azetidin-2-yl-C_1-2-alkyl, azetidin-3-yl-C_1-2-alkyl, pyrrolidin-2-yl-C_1-2-alkyl, pyrrolidin-3-yl, pyrrolidin-3-yl-C_1-2-alkyl, piperidin-2-yl-C_1-2-alkyl, piperidin-3-yl, piperidin-3-yl-C_1-2-alkyl, piperidin-4-yl or piperidin-4-yl-C_1-2-alkyl group, wherein the abovementioned groups may each be substituted by one or two C_1-3-alkyl groups, while by the aryl groups mentioned in the definition of the groups mentioned above are meant phenyl or naphthyl groups which may be mono- or disubstituted by R_hindependently of one another, while the substituents may be identical or different and R_hdenotes a fluorine, chlorine, bromine or iodine atom, a trifluoromethyl, cyano, nitro, amino, aminocarbonyl, aminosulphonyl, methylsulphonyl, acetylamino, methylsulphonylamino, C_1-3-alkyl, cyclopropyl, ethenyl, ethynyl, hydroxy, C_1-3-alkyloxy, difluoromethoxy or trifluoromethoxy group,

by the heteroaryl groups mentioned in the definition of the groups mentioned above is meant a pyrrolyl, furanyl, thienyl, pyridyl, indolyl, benzofuranyl, benzothiophenyl, quinolinyl or isoquinolinyl group,

or a pyrrolyl, furanyl, thienyl or pyridyl group wherein one or two methyne groups are replaced by nitrogen atoms,

or an indolyl, benzofuranyl, benzothiophenyl, quinolinyl or isoquinolinyl group wherein one to three methyne groups are replaced by nitrogen atoms,

or a 1,2-dihydro-2-oxo-pyridinyl, 1,4-dihydro-4-oxo-pyridinyl, 2,3-dihydro-3-oxo-pyridazinyl, 1,2,3,6-tetrahydro-3,6-dioxo-pyridazinyl, 1,2-dihydro-2-oxo-pyrimidinyl, 3,4-dihydro-4-oxo-pyrimidinyl, 1,2,3,4-tetrahydro-2,4-dioxo-pyrimidinyl, 1,2-dihydro-2-oxo-pyrazinyl, 1,2,3,4-tetrahydro-2,3-dioxo-pyrazinyl, 2,3-dihydro-2-oxo-indolyl, 2,3-dihydrobenzofuranyl, 2,3-dihydro-2-oxo-1 H-benzimidazolyl, 2,3-dihydro-2-oxo-benzoxazolyl, 1,2-dihydro-2-oxo-quinolinyl, 1,4-dihydro-4-oxo-quinolinyl, 1,2-dihydro-1-oxo-isoquinolinyl, 1,4-dihydro-4-oxo-cinnolinyl, 1,2-dihydro-2-oxo-quinazolinyl, 1,4-dihydro-4-oxo-quinazolinyl, 1,2,3,4-tetrahydro-2,4-dioxo-quinazolinyl, 1,2-dihydro-2-oxoquinoxalinyl, 1,2,3,4-tetrahydro-2,3-dioxo-quinoxalinyl, 1,2-dihydro-1-oxo-phthalazinyl, 1,2,3,4-tetrahydro-1,4-dioxo-phthalazinyl, chromanyl, cumarinyl, 2,3-dihydro-benzo[1,4]dioxinyl or 3,4-dihydro-3-oxo-2H-benzo[1,4]oxazinyl group,

- wherein the abovementioned heteroaryl groups may be substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

while, unless otherwise stated, the abovementioned alkyl, alkenyl and alkynyl groups may be straight-chain or branched,

as well as the derivatives which are N-oxidised or methylated or ethylated at the cyclic nitrogen atom in the 9 position of the xanthine skeleton,

as well as the derivatives wherein the 2-oxo, the 6-oxo- or the 2-oxo- and the 6-oxo group of the xanthine skeleton are replaced by thioxo groups,

with the proviso that the compounds wherein

R¹denotes a hydrogen atom, a methyl, propyl, 2-hydroxypropyl, aminocarbonyl-methyl or benzyl group,

R²denotes a methyl group,

R³denotes a C_1-8-alkyl group, a benzyl group optionally substituted by a fluorine, chlorine or bromine atom or by a methyl group, a 1-phenylethyl or 2-phenylethyl group, a 2-propen-1-yl, 2-buten-1-yl, 3-chloro-2-buten-1-yl or 2-methyl-2-propen-1-yl group

and

R⁴denotes a piperazin-1-yl group, are excluded,

and with the proviso that the compounds wherein

R¹denotes a hydrogen atom or a methyl group,

R²denotes a hydrogen atom or a methyl group,

R³denotes a methyl group

and

R⁴denotes a 3-aminopropyl, 3-[di-(C_1-3-alkyl)amino]-propyl, 1-phenyl-3-[di-(C_1-3-alkyl)amino]-propyl, 1-phenyl-3-methyl-3-(dimethylamino)-propyl, 1-(4-chlorophenyl)-3-(dimethylamino)-propyl, 1-phenyl-2-methyl-3-(dimethylamino)-propyl,

1-(3-methoxyphenyl)-3-(dimethylamino)-propyl or a 4-aminobutyl group, are excluded,

and with the proviso that the compound

1,3,7-trimethyl-8-(1-aminocyclohexyl)-xanthine

is excluded,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

The carboxy groups mentioned in the definition of the abovementioned groups may be replaced by a group which can be converted into a carboxy group in vivo or by a group which is negatively charged under physiological conditions,

and furthermore the amino and imino groups mentioned in the definition of the abovementioned groups may be substituted by a group which can be cleaved in vivo. Such groups are described for example in WO 98/46576 and by N. M. Nielsen et al. in International Journal of Pharmaceutics 39, 75-85 (1987).

By a group which can be converted in vivo into a carboxy group is meant, for example, a hydroxymethyl group, a carboxy group esterified with an alcohol wherein the alcohol moiety is preferably a C_1-6-alkanol, a phenyl-C_1-3-alkanol, a C_3-9-cycloalkanol, while a C_5-8-cycloalkanol may additionally be substituted by one or two C_1-3-alkyl groups, a C_5-8-cycloalkanol wherein a methylene group in the 3 or 4 position is replaced by an oxygen atom or by an imino group optionally substituted by a C_1-3-alkyl, phenyl-C_1-3-alkyl, phenyl-C_1-3-alkoxycarbonyl or C_2-6-alkanoyl group and the cycloalkanol moiety may additionally be substituted by one or two C_1-3-alkyl groups, a C_4-7-cycloalkenol, a C_3-5-alkenol, a phenyl-C_3-5-alkenol, a C_3-5-alkynol or phenyl-C_3-5-alkynol with the proviso that no bonds to the oxygen atom start from a carbon atom which carries a double or triple bond, a C_3-5-cycloalkyl-C_1-3-alkanol, a bicycloalkanol with a total of 8 to 10 carbon atoms which may additionally be substituted in the bicycloalkyl moiety by one or two C_1-3-alkyl groups, a 1,3-dihydro-3-oxo-1-isobenzofuranol or an alcohol of formula

R_pâ€”COâ€”Oâ€”(R_qCR_r)â€”OH,

wherein

R_pdenotes a C_1-8-alkyl, C_5-7-cycloalkyl, phenyl or phenyl-C_1-3-alkyl group,

R_qdenotes a hydrogen atom, a C_1-3-alkyl, C_5-7-cycloalkyl or phenyl group and

R_rdenotes a hydrogen atom or a C_1-3-alkyl group,

by a group which is negatively charged under physiological conditions is meant, for example, a tetrazol-5-yl, phenylcarbonylaminocarbonyl, trifluoromethylcarbonylaminocarbonyl, C_1-6-alkylsulphonylamino, phenylsulphonylamino, benzylsulphonylamino, trifluoromethylsulphonylamino, C_1-6-alkylsulphonylaminocarbonyl, phenylsulphonylaminocarbonyl, benzylsulphonylaminocarbonyl or perfluoro-C_1-6-alkylsulphonylaminocarbonyl group

and by a group which can be cleaved in vivo from an imino or amino group is meant, for example, a hydroxy group, an acyl group such as a phenylcarbonyl group optionally mono- or disubstituted by fluorine, chlorine, bromine or iodine atoms, by C_1-3-alkyl or C_1-3-alkoxy groups, while the substituents may be identical or different, a pyridinoyl group or a C_1-16-alkanoyl group such as the formyl, acetyl, propionyl, butanoyl, pentanoyl or hexanoyl group, a 3,3,3-trichloropropionyl or allyloxycarbonyl group, a C_1-16-alkoxycarbonyl or C_1-16-alkylcarbonyloxy group, wherein hydrogen atoms may be wholly or partially replaced by fluorine or chlorine atoms such as the methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, tert.butoxycarbonyl, pentoxycarbonyl, hexoxycarbonyl, octyloxycarbonyl, nonyloxycarbonyl, decyloxycarbonyl, undecyloxycarbonyl, dodecyloxycarbonyl, hexadecyloxycarbonyl, methylcarbonyloxy, ethylcarbonyloxy, 2,2,2-trichloroethylcarbonyloxy, propylcarbonyloxy, isopropylcarbonyloxy, butylcarbonyloxy, tert.butylcarbonyloxy, pentylcarbonyloxy, hexylcarbonyloxy, octylcarbonyloxy, nonylcarbonyloxy, decylcarbonyloxy, undecylcarbonyloxy, dodecylcarbonyloxy or hexadecylcarbonyloxy group, a phenyl-C_1-6-alkoxycarbonyl group such as the benzyloxycarbonyl, phenylethoxycarbonyl or phenylpropoxycarbonyl group, a 3-amino-propionyl group wherein the amino group may be mono- or disubstituted by C_1-6-alkyl or C_3-7-cycloalkyl groups and the substituents may be identical or different, a C_1-3-alkylsulphonyl-C_2-4-alkoxycarbonyl,

C_1-3-alkoxy-C_2-4-alkoxy-C_2-4-alkoxycarbonyl, R_pâ€”COâ€”Oâ€”(R_gCR_r)â€”Oâ€”CO, C_1-6-alkyl-COâ€”NHâ€”(R_sCR_t)â€”Oâ€”Câ€” or C_1-6-alkyl-COâ€”Oâ€”(R_sCR_t)â€”(R_sCR_t)â€”Oâ€”COâ€” group, wherein R_pto R_rare as hereinbefore defined,

- R_sand R_t, which may be identical or different, denote hydrogen atoms or C_1-3-alkyl groups.

Moreover, unless otherwise stated, the saturated alkyl and alkoxy moieties containing more than 2 carbon atoms mentioned in the definitions above also include the branched isomers thereof such as the isopropyl, tert.butyl, isobutyl group, etc.

R¹and R²may denote, for example a hydrogen atom, a methyl, ethyl, propyl, 2-propyl, butyl, 2-butyl, 2-methylpropyl, 2-propen-1-yl, 2-propyn-1-yl, cyclopropylmethyl, benzyl, 2-phenylethyl, phenylcarbonylmethyl, 3-phenylpropyl, 2-hydroxyethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-(d imethylamino)ethyl, 2-(di-ethylamino)ethyl, 2-(pyrrolidino)ethyl, 2-(piperidino)ethyl, 2-(morpholino)ethyl, 2-(piperazino)ethyl, 2-(4-methylpiperazino)ethyl, 3-hydroxypropyl, 3-methoxypropyl, 3-ethoxypropyl, 3-(dimethylamino)propyl, 3-(diethylamino)propyl, 3-(pyrrolidino)propyl, 3-(piperidino)propyl, 3-(morpholino)propyl, 3-(piperazino)-propyl, 3-(4-methylpiperazino)propyl, carboxymethyl, (methoxycarbonyl)methyl, (ethoxycarbonyl)methyl, 2-carboxyethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxy-carbonyl)ethyl, 3-carboxypropyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)-propyl, (aminocarbonyl)methyl, (methylaminocarbonyl)methyl, (dimethylamino-carbonyl)methyl, (pyrrolidinocarbonyl)methyl, (piperidinocarbonyl)methyl, (morpholinocarbonyl)methyl, 2-(aminocarbonyl)ethyl, 2-(methylaminocarbonyl)ethyl, 2-(dimethylaminocarbonyl)ethyl, 2-(pyrrolidinocarbonyl)ethyl, 2-(piperidinocarbonyl)-ethyl, 2-(morpholinocarbonyl)ethyl, cyanomethyl or 2-cyanoethyl group.

R³may denote, for example, a methyl, ethyl, propyl, 2-propyl, butyl, 2-butyl, 2-methylpropyl, pentyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, cyclopropylmethyl, (1-methylcyclopropyl)methyl, (2-methylcyclopropyl)methyl, cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, 2-(cyclopropyl)ethyl, 2-propen-1-yl, 2-methyl-2-propen-1-yl, 3-phenyl-2-propen-1-yl, 2-buten-1-yl, 4,4,4-trifluoro-2-buten-1-yl, 3-buten-1-yl, 2-chloro-2-buten-1-yl, 2-bromo-2-buten-1-yl chloro-2-buten-1-yl, 3-bromo-2-buten-1-yl, 2-methyl-2-buten-1-yl, 3-methyl-2-buten-1-yl, 2,3-dimethyl-2-buten-1-yl, 3-trifluoromethyl-2-buten-1-yl, 3-methyl-3-buten-1-yl, 1-cyclopenten-1-yl methyl, (2-methyl-1-cyclopenten-1-yl)methyl, 1-cyclohexen-1-yl methyl, 2-(1-cyclopenten-1-yl)ethyl, 2-propyn-1-yl, 2-butyn-1-yl, 3-butyn-1-yl, phenyl, methylphenyl, benzyl, a fluorobenzyl, chlorobenzyl, bromobenzyl, methylbenzyl, methoxybenzyl, 1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, 2-furanylmethyl, 3-furanylmethyl, 2-thienylmethyl- or 3-thienylmethyl group.

R⁴may denote, for example, a 3-aminopyrrolidin-1-yl, 3-aminopiperidin-1-yl, 3-(methylamino)-piperidin-1-yl, 3-(ethylamino)-piperidin-1-yl, 3-(dimethylamino)-piperidin-1-yl, 3-(diethylamino)-piperidin-1-yl, 3-[(2-hydroxyethyl)amino]-piperidin-1-yl, 3-[N-methyl-N-(2-hydroxyethyl)-amino]-piperidin-1-yl, 3-[(3-hydroxypropyl)amino]-piperidin-1-yl, 3-[N-methyl-N-(3-hydroxypropyl)-amino]-piperidin-1-yl, 3-[(carboxy-methyl)amino]-piperidin-1-yl, 3-[(methoxycarbonylmethyl)amino]-piperidin-1-yl, 3-[(ethoxycarbonylmethyl)amino]-piperidin-1-yl, 3-[N-methyl-N-(methoxycarbonyl-methyl)-amino]-piperidin-1-yl, 3-[N-methyl-N-(ethoxycarbonylmethyl)-amino]-piperidin-1-yl, 3-[(2-carboxyethyl)amino]-piperidin-1-yl, 3-{[2-(methoxycarbonypethyl]amino}-piperidin-1-yl, 3-{[2-(ethoxycarbonypethyl]amino}-piperidin-1-yl, 3-{N-methyl-N[2-(methoxycarbonypethyl]amino}-piperidin-1-yl, 3-{N-methyl-N-[2-(ethoxycarbonypethyl]amino}-piperidin-1-yl, 3-[(aminocarbonylmethyl)-amino]-piperidin-1-yl, 3-[(methylaminocarbonylmethyl)amino]-piperidin-1-yl, 3-[(dimethylaminocarbonylmethypamino]-piperidin-1-yl, 3-[(ethylaminocarbonylmethypamino]-piperidin-1-yl, 3-[(diethylaminocarbonylmethyl)amino]-piperidin-1-yl, 3-[(pyrrolidin-1-ylcarbonyl-methyl)amino]-piperidin-1-yl, 3-[(2-cyanopyrrolidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(4-cyanothiazolidin-3-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(2-aminocarbonylpyrrolidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(2-carboxypyrrolidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(2-methoxycarbonylpyrrolidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(2-ethoxycarbonylpyrrolidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(piperidin-1-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-[(morpholin-4-ylcarbonylmethyl)amino]-piperidin-1-yl, 3-amino-2-methyl-piperidin-1-yl, 3-amino-3-methyl-piperidin-1-yl, 3-amino-4-methyl-piperidin-1-yl, 3-amino-5-methyl-piperidin-1-yl, 3-amino-6-methyl-piperidin-1-yl, 2-amino-8-aza-bicyclo[3.2.1]oct-8-yl, 6-amino-2-aza-bicyclo[2.2.2]oct-2-yl, 4-aminopiperidin-1-yl, 3-amino-hexahydroazepin-1-yl, 4-amino-hexahydroazepin-1-yl, piperazin-1-yl, [1,4]diazepan-1-yl, 3-aminocyclopentyl, 3-aminocyclohexyl, 3-(methylamino)-cyclohexyl, 3-(ethylamino)-cyclohexyl, 3-(dimethylamino)-cyclohexyl, 3-(diethylamino)-cyclohexyl, 4-aminocyclohexyl, (2-aminocyclopropyl)amino, (2-aminocyclobutyl)amino, (3-aminocyclobutyl)amino, (2-aminocyclopentyl)amino, (3-aminocyclopentyl)amino, (2-aminocyclohexyl)amino or (3-aminocyclohexyl)amino group.

A sub-group deserving special mention relates to those compounds of general formula I wherein R¹to R⁴are as hereinbefore defined, with the extra proviso that the compounds wherein R⁴denotes an optionally substituted piperazin-1-yl or [1,4]diazepan-1-yl group are excluded, the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A second sub-group deserving special mention relates to those compounds of general formula I wherein

R¹denotes a hydrogen atom,

a C_1-6-alkyl group,

a C_3-6-alkenyl group,

a C_3-4-alkenyl group which is substituted by a C_1-2-alkyloxy-carbonyl group,

a C_3-6-alkynyl group,

a C_3-6-cycloalkyl-C_1-3-alkyl group,

a phenyl group which may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl, hydroxy or methoxy group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein

- R¹⁰denotes a hydrogen atom, a fluorine, chlorine or bromine atom,
- a C_1-4-alkyl, trifluoromethyl, hydroxymethyl, C_3-6-cycloalkyl, ethynyl or phenyl group,
- a hydroxy, C_1-4-alkyloxy, difluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, phenoxy, benzyloxy, 2-propen-1-yloxy, 2-propyn-1-yloxy, cyano-C_1-2-alkyloxy, C_1-2-alkylsulphonyloxy, phenylsulphonyloxy, carboxy-C_1-3-alkyloxy, C_1-3-alkyloxy-carbonyl-C_1-3-alkyloxy, aminocarbonyl-C_1-3-alkyloxy, C_1-2-alkyl-aminocarbonyl-C_1-3-alkyloxy, di-(C_1-2-alkyl)aminocarbonyl-C_1-3-alkyloxy, pyrrolidin-1-yl-carbonyl-C_1-3-alkyloxy, piperidin-1-ylcarbonyl-C_1-3-alkyloxy, morpholin-4-ylcarbonyl-C_1-3-alkyloxy, methylsulphanylmethoxy, methylsulphinylmethoxy, methylsulphonylmethoxy, C_3-6-cycloalkyloxy or C_3-6-cycloalkyl-C_1-2-alkyloxy group,
- a carboxy, C_1-3-alkyloxycarbonyl, carboxy-C_1-3-alkyl, C_1-3-alkyloxy-carbonyl-C_1-3-alkyl, aminocarbonyl, C_1-2-alkylaminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, morpholin-4-ylcarbonyl or cyano group,
- a nitro, amino, C_1-2-alkylamino, di-(C_1-2-alkyl)amino, cyano-C_1-2-alkylamino, [N-(cyano-C_1-2-alkyl)-Nâ€”C_1-2-alkyl-amino], C_1-2-alkyloxy-carbonyl-C_1-2-alkylamino, C_1-2-alkyl-carbonylamino, C_1-2-alkyloxy-carbonylamino, C_1-3-alkylsulphonylamino, bis-(C_1-2-alkylsulphonyl)-amino, aminosulphonylamino, C_1-2-alkylamino-sulphonylamino, di-(C_1-2-alkyl)amino-sulphonylamino, morpholin-4-yl-sulphonylamino, (C_1-2-alkylamino)thiocarbonylamino, (C_1-2-alkyloxy-carbonylamino)carbonylamino, aminocarbonylamino, C_1-2-alkyl-aminocarbonylamino, di-(C_1-2-alkyl)aminocarbonylamino or morpholin-4-ylcarbonylamino group,
- a 2-oxo-imidazolidin-1-yl, 3-methyl-2-oxo-imidazolidin-1-yl, 2,4-dioxo-imidazolidin-1-yl, 3-methyl-2,4-dioxo-imidazolidin-1-yl, 2,5-dioxo-imidazolidin-1-yl, 3-methyl-2,5-dioxo-imidazolidin-1-yl, 2-oxo-hexahydropyrimidin-1-yl or 3-methyl-2-oxo-hexahydropyrimidin-1-yl group,
- or
- a C_1-2-alkylsulphanyl, C_1-2-alkylsulphinyl, C_1-2-alkylsulphonyl, aminosulphonyl, C_1-2-alkylaminosulphonyl or di-(C_1-2-alkyl)aminosulphonyl group,
- and R¹¹and R¹², which may be identical or different, denote a hydrogen, fluorine, chlorine or bromine atom or
- a methyl, cyano, trifluoromethyl or methoxy group,
- or, R¹¹together with R¹², if they are bound to adjacent carbon atoms, also denote a methylenedioxy, difluoromethylenedioxy, 1,3-propylene or 1,4-butylene group,

a phenyl-C_1-3-alkyl group wherein the alkyl moiety is substituted by a carboxy, C_1-2-alkyloxy-carbonyl, aminocarbonyl, C_1-2-alkylaminocarbonyl or di-(C_1-2-alkyl)amino-carbonyl group,

a phenyl-C_2-3-alkenyl group, wherein the phenyl moiety may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl or methoxy group,

a phenyl-(CH₂)_m-A-(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined and

- A denotes a carbonyl, hydroxyiminomethylene or C_1-2-alkyloxyiminomethylene group, m denotes the number 0 or 1 and n denotes the number 1 or 2,

a phenylcarbonylmethyl group wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined and the methyl moiety is substituted by a methyl or ethyl group,

a phenylcarbonylmethyl group wherein two adjacent hydrogen atoms of the phenyl moiety are replaced by a â€”Oâ€”COâ€”NH, â€”NHâ€”COâ€”NH, â€”Nâ• CHâ€”NH, â€”Nâ• CHâ€”O or â€”Oâ€”CH₂â€”COâ€”NHâ€” bridge, wherein the abovementioned bridges may be substituted by one or two methyl groups,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹², m and n are as hereinbefore defined and

- B denotes a methylene group which is substituted by a hydroxy or C_1-2-alkyloxy group and is optionally additionally substituted by a methyl group,

a naphthylmethyl or naphthylethyl group, wherein the naphthyl moiety is substituted in each case by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined,

a [1,4]naphthoquinon-2-yl, chromen-4-on-3-yl or 1-oxoindan-2-yl group,

a heteroaryl-C_1-3-alkyl group, wherein the term heteroaryl denotes a pyrrolyl, imidazolyl, triazolyl, furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, benzimidazolyl, 2,3-dihydro-2-oxo-1H-benzimidazolyl, indazolyl, benzofuranyl, 2,3-dihydrobenzofuranyl, benzoxazolyl, dihydro-2-oxo-benzoxazolyl, benzoisoxazolyl, benzothiophenyl, benzothiazolyl, benzoisothiazolyl, quinolinyl, 1,2-dihydro-2-oxo-quinolinyl, isoquinolinyl, 1,2-dihydro-1-oxo-isoquinolinyl, cinnolinyl, quinazolinyl, 1,2-dihydro-2-oxo-quinazolinyl, 1,2-dihydro-1-oxo-phthalazin-4-yl, cumarinyl or 3,4-dihydro-3-oxo-2H-benzo[1,4]oxazinyl group,

- wherein the abovementioned heteroaryl groups may be substituted at carbon atoms by a fluorine, chlorine or bromine atom, by a methyl, trifluoromethyl, cyano, aminocarbonyl, aminosulphonyl, methylsulphonyl, nitro, amino, acetylamino, methylsulphonylamino, methoxy, difluoromethoxy or trifluoromethoxy group and the imino groups of the abovementioned heteroaryl groups may be substituted by methyl or ethyl groups,
- a furanyl-A-CH₂, thienyl-A-CH₂, thiazolyl-A-CH₂or pyridyl-A-CH₂group, wherein A is as hereinbefore defined,

a furanyl-Bâ€”CH₂, thienyl-Bâ€”CH₂, thiazolyl-Bâ€”CH₂or pyridyl-Bâ€”CH₂group, wherein B is as hereinbefore defined,

a C_1-4-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-6-cycloalkyl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a C_3-6-cycloalkyl-(CH₂)_mâ€”Bâ€”(CH₂), group, wherein B, m and n are as hereinbefore defined,

a R²¹-A-(CH₂), group wherein R²¹denotes a C_1-2-alkyloxycarbonyl, aminocarbonyl, C_1-2-alkylaminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl or morpholin-4-yl-carbonyl group and A and n are as hereinbefore defined,

a phenyl-D-C_1-3-alkyl group wherein the phenyl moiety is optionally substituted by a fluorine, chlorine or bromine atom, a methyl, trifluoromethyl or methoxy group and D denotes an oxygen or sulphur atom, a sulphinyl or sulphonyl group,

a C_1-4-alkyl group substituted by a group R_a, wherein

- R_adenotes a cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group,

a C_2-4-alkyl group substituted by a group R_b, wherein

- R_bdenotes a hydroxy, C_1-3-alkyloxy, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl, 4-methyl-piperazin-1-yl or 4-ethyl-piperazin-1-yl group and is isolated from the cyclic nitrogen atom in the 1 position of the xanthine skeleton by at least two carbon atoms,

or an amino or benzoylamino group,

R²denotes a hydrogen atom,

a C_1-6-alkyl group,

a C_2-4-alkenyl group,

a C_3-4-alkynyl group,

a C_3-6-cycloalkyl group,

a C_3-6-cycloalkyl-C_1-3-alkyl group,

a tetrahydrofuran-3-yl, tetrahydropyran-3-yl, tetrahydropyran-4-yl, tetrahydrofuranylmethyl or tetrahydropyranylmethyl group,

a phenyl group which is optionally substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety is optionally substituted by a fluorine, chlorine or bromine atom, a methyl, trifluoromethyl, dimethylamino, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,

a phenyl-C_2-3-alkenyl group, wherein the phenyl moiety may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl or methoxy group,

a phenylcarbonyl-C_1-2-alkyl group wherein the phenyl moiety is optionally substituted by a fluorine, chlorine or bromine atom, a methyl, trifluoromethyl, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,

a heteroaryl-C_1-3-alkyl group, wherein the term heteroaryl is as hereinbefore defined,

a furanylcarbonylmethyl, thienylcarbonylmethyl, thiazolylcarbonylmethyl or pyridylcarbonylmethyl group,

a C_1-4-alkyl-carbonyl-C_1-2-alkyl group,

a C_3-6-cycloalkyl-carbonyl-C_1-2-alkyl group,

a phenyl-D-C_1-3-alkyl group wherein the phenyl moiety is optionally substituted by a fluorine, chlorine or bromine atom, a methyl, trifluoromethyl, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group, and D is as hereinbefore defined, or

a C_1-4-alkyl group substituted by a group R_a, wherein R_ais as hereinbefore defined, or

a C_2-4-alkyl group substituted by a group R_b, wherein R_bis as hereinbefore defined and is isolated from the cyclic nitrogen atom in the 3 position of the xanthine skeleton by at least two carbon atoms,

R³denotes a C_1-3-alkyl group substituted by the group R_c, wherein

- R_cdenotes a C_3-7-cycloalkyl group optionally substituted by one or two C_1-3-alkyl groups,
- a C_5-7-cycloalkenyl group optionally substituted by one or two C_1-3-alkyl groups or
- an aryl group or
- a furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrimidyl or pyrazinyl group, wherein the abovementioned heterocyclic groups may each be substituted by one or two C_1-3-alkyl groups or by a fluorine, chlorine, bromine or iodine atom or by a trifluoromethyl, cyano or C_1-3-alkyloxy group,

a C_3-8-alkenyl group,

a C_3-6-alkenyl group substituted by a fluorine, chlorine or bromine atom, or a trifluoromethyl group,

a C_3-6-alkynyl group,

an aryl group or

an aryl-C_2-4-alkenyl group,

and

R⁴denotes an azetidin-1-yl or pyrrolidin-1-yl group which is substituted in the 3 position by an R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein

- R_edenotes a hydrogen atom or a C_1-3-alkyl group and
- R_ddenotes a hydrogen atom or a C_1-3-alkyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted in the 4 position or in the 5 position by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein the methylene group is replaced in the 2 position or in the 6 position by a carbonyl group,

a piperidin-1-yl or hexahydroazepin-1-yl group substituted in the 3 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein in each case two hydrogen atoms on the carbon skeleton of the piperidin-1-yl or hexahydroazepin-1-yl group are replaced by a straight-chain alkylene bridge, this bridge containing 2 to 5 carbon atoms if the two hydrogen atoms are located on the same carbon atom, or 1 to 4 carbon atoms if the hydrogen atoms are located on adjacent carbon atoms, or 1 to 4 carbon atoms if the hydrogen atoms are located on carbon atoms which are separated by one atom, or 1 to 3 carbon atoms if the two hydrogen atoms are located on carbon atoms separated by two atoms,

an azetidin-1-yl, pyrrolidin-1-yl, piperidin-1-yl or hexahydroazepin-1-yl group which is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a 3-imino-piperazin-1-yl, 3-imino-[1,4]diazepan-1-yl or 5-imino-[1,4]diazepan-1-yl group optionally substituted by one or two C_1-3-alkyl groups on the carbon skeleton,

a [1,4]diazepan-1-yl group optionally substituted by one or two C_1-3-alkyl groups, which is substituted in the 6 position by an amino group,

a C_3-7-cycloalkyl group which is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl group which is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms are separated from one another at the cycloalkyl moiety by at least two carbon atoms,

a Nâ€”(C_3-7-cycloalkyl)-Nâ€”(C_1-3-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms are separated from one another at the cycloalkyl moiety by at least two carbon atoms,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a Nâ€”(C_3-7-cycloalkyl)-Nâ€”(C_1-3-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a Nâ€”(C_3-7-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a C_1-3-alkyl group and
- R¹⁶denotes a R¹⁷â€”C_2-3-alkyl group, wherein the C_2-3-alkyl moiety is straight-chained and may be substituted by one to four C_1-3-alkyl groups, which may be identical or different, or by an aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, (2-cyano-pyrrolidin-1-yl)carbonyl, thiazolidin-3-yl-carbonyl, (4-cyano-thiazolidin-3-yl)carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group and
- R¹â€² denotes an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

an amino group substituted by the group R²⁰, wherein

- R²⁰denotes an azetidin-3-yl, azetidin-2-ylmethyl, azetidin-3-ylmethyl, pyrrolidin-3-yl, pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-3-yl, piperidin-4-yl, piperidin-2-ylmethyl, piperidin-3-ylmethyl or piperidin-4-ylmethyl group, wherein the groups mentioned for R²⁰may each be substituted by one or two C_1-3-alkyl groups,

an amino group substituted by the groups R¹⁵and R²⁰, wherein

- R¹⁵and R²⁰are as hereinbefore defined, wherein the groups mentioned for
- R²⁰may each be substituted by one or two C_1-3-alkyl groups,

a R¹⁹â€”C_3-4-alkyl group wherein the C_3-4-alkyl moiety is straight-chained and may be substituted by the group R¹⁵and may additionally be substituted by one or two C_1-3-alkyl groups, wherein R¹⁵is as hereinbefore defined and R¹⁹denotes an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

a pyrrolidin-3-yl, piperidin-3-yl, piperidin-4-yl, hexahydroazepin-3-yl or hexahydroazepin-4-yl group, which is substituted in the 1 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)amino group,

or an azetidin-2-yl-C_1-2-alkyl, azetidin-3-yl-C_1-2-alkyl, pyrrolidin-2-yl-C_1-2-alkyl, pyrrolidin-3-yl, pyrrolidin-3-yl-C_1-2-alkyl, piperidin-2-yl-C_1-2-alkyl, piperidin-3-yl, piperidin-3-yl-C_1-2-alkyl, piperidin-4-yl or piperidin-4-yl-C_1-2-alkyl group, wherein the abovementioned groups may each be substituted by one or two C_1-3-alkyl groups, while by the aryl groups mentioned in the definition of the groups mentioned above are meant phenyl or naphthyl groups which may be mono- or disubstituted independently of one another by R_h, while the substituents may be identical or different and R_hdenotes a fluorine, chlorine, bromine or iodine atom, a trifluoromethyl, cyano, nitro, amino, C_1-3-alkyl, cyclopropyl, ethenyl, ethynyl, hydroxy, C_1-3-alkyloxy, difluoromethoxy or trifluoromethoxy group and

unless otherwise stated, the abovementioned alkyl and alkenyl groups may be straight-chained or branched,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A third sub-group deserving special mention relates to those compounds of general formula I wherein

R¹, R²and R³are as hereinbefore defined and

R⁴denotes an azetidin-1-yl or pyrrolidin-1-yl group which is substituted in the 3 position by a R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein

- R_edenotes a hydrogen atom or a C_1-3-alkyl group and
- R_ddenotes a hydrogen atom or a C_1-3-alkyl group,

a piperidin-1-yl or hexahydroazepin-1-yl group which is substituted in the 3 position or in the 4 position by a R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein R_eand R_dare as hereinbefore defined,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted in the 4 position or in the 5 position by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein the methylene group in the 2 position or in the 6 position is replaced by a carbonyl group,

a piperidin-1-yl or hexahydroazepin-1-yl group substituted in the 3 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein in each case two hydrogen atoms on the carbon skeleton of the piperidin-1-yl or hexahydroazepin-1-yl group are replaced by a straight-chain alkylene bridge, this bridge containing 2 to 5 carbon atoms if the two hydrogen atoms are located on the same carbon atom, or 1 to 4 carbon atoms, if the hydrogen atoms are located on adjacent carbon atoms, or 1 to 4 carbon atoms, if the hydrogen atoms are located on carbon atoms separated by one atom, or 1 to 3 carbon atoms if the two hydrogen atoms are located on carbon atoms separated by two atoms,

a C_3-7-cycloalkyl group which is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl group which is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms at the cycloalkyl moiety are separated from one another by at least two carbon atoms,

a Nâ€”(C_3-7-cycloalkyl)-Nâ€”(C_1-3-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein the two nitrogen atoms at the cycloalkyl moiety are separated from one another by at least two carbon atoms,

a C_3-7-cycloalkylamino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a Nâ€”(C_3-7-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

a C_3-7-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

a Nâ€”(C_3-7-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl or a di-(C_1-3-alkyl)amino-C_1-3-alkyl group,

an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a C_1-4-alkyl group and
- R¹⁶denotes a R¹⁷â€”C_2-3-alkyl group, wherein the C_2-3-alkyl moiety is straight-chained and may be substituted by one to four C_1-3-alkyl groups, which may be identical or different, or may be substituted by an aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, (2-cyano-pyrrolidin-1-yl-)carbonyl, thiazolidin-3-yl-carbonyl, (4-cyano-thiazolidin-3-yl)carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group and
- R¹⁷denotes an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group,

an amino group substituted by the group R²⁰, wherein

- R²⁰denotes an azetidin-3-yl, azetidin-2-ylmethyl, azetidin-3-ylmethyl, pyrrolidin-3-yl, pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-3-yl, piperidin-4-yl, piperidin-2-ylmethyl, piperidin-3-ylmethyl or piperidin-4-ylmethyl group, wherein the groups mentioned for R²⁰may each be substituted by one or two C_1-3-alkyl groups,

an amino group substituted by the groups R¹⁵and R²⁰wherein

- R¹⁵and R²⁰are as hereinbefore defined, wherein the groups mentioned for
- R²⁰may each be substituted by one or two C_1-3-alkyl groups,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

Preferred compounds of the above general formula I are those wherein

R¹denotes a hydrogen atom,

a C_1-6-alkyl group,

a C_3-6-alkenyl group,

a C_3-4-alkenyl group which is substituted by a C_1-2-alkyloxy-carbonyl group,

a C_3-6-alkynyl group,

a C_3-6-cycloalkyl-C_1-3-alkyl group,

a phenyl group which may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl, hydroxy or methoxy group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein

- R¹⁰denotes a hydrogen atom, a fluorine, chlorine or bromine atom,
- a C_1-4-alkyl, trifluoromethyl, hydroxymethyl, C_3-6-cycloalkyl, ethynyl or phenyl group,
- a hydroxy, C_1-4-alkyloxy, difluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, phenoxy, benzyloxy, 2-propen-1-yloxy, 2-propyn-1-yloxy, cyano-C_1-2-alkyloxy, C_1-2-alkylsulphonyloxy, phenylsulphonyloxy, carboxy-C_1-3-alkyloxy, C_1-3-alkyloxy-carbonyl-C_1-3-alkyloxy, aminocarbonyl-C_1-3-alkyloxy, C_1-2-alkyl-aminocarbonyl-C_1-3-alkyloxy, di-(C_1-2-alkyl)aminocarbonyl-C_1-3-alkyloxy, pyrrolidin-1-yl-carbonyl-C_1-3-alkyloxy, piperidin-1-ylcarbonyl-C_1-3-alkyloxy, morpholin-4-ylcarbonyl-C_1-3-alkyloxy, methylsulphanylmethoxy, methylsulphinylmethoxy, methylsulphonylmethoxy, C_3-6-cycloalkyloxy or C_3-6-cycloalkyl-C_1-2-alkyloxy group,

a carboxy, C_1-3-alkyloxycarbonyl, carboxy-C_1-3-alkyl, C_1-3-alkyloxy-carbonyl-C_1-3-alkyl, aminocarbonyl, C_1-2-alkylaminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, morpholin-4-ylcarbonyl or cyano group,

a nitro, amino, C_1-2-alkylamino, di-(C_1-2-alkyl)amino, cyano-C_1-2-alkylamino, [N-(cyano-C_1-2-alkyl)-Nâ€”C_1-2-alkyl-amino], C_1-2-alkyloxy-carbonyl-C_1-2-alkylamino, C_1-2-alkylcarbonylamino, C_1-2-alkyloxy-carbonylamino, C_1-3-alkylsulphonylamino, bis-(C_1-2-alkylsulphonyl)-amino, aminosulphonylamino, C_1-2-alkylamino-sulphonylamino, di-(C_1-2-alkyl)amino-sulphonylamino, morpholin-4-yl-sulphonylamino, (C_1-2-alkylamino)thiocarbonylamino, (C_1-2-alkyloxy-carbonylamino)carbonylamino, aminocarbonylamino, C_1-2-alkylaminocarbonylamino, di-(C_1-2-alkyl)aminocarbonylamino or morpholin-4-ylcarbonylamino group,

- a 2-oxo-imidazolidin-1-yl, 3-methyl-2-oxo-imidazolidin-1-yl, 2,4-dioxo-imidazolidin-1-yl, 3-methyl-2,4-dioxo-imidazolidin-1-yl, 2,5-dioxo-imidazolidin-1-yl, 3-methyl-2,5-dioxo-imidazolidin-1-yl, 2-oxo-hexahydropyrimidin-1-yl or 3-methyl-2-oxo-hexahydropyrimidin-1-yl group,
- or
- a C_1-2-alkylsulphanyl, C_1-2-alkylsulphinyl, C_1-2-alkylsulphonyl, aminosulphonyl, C_1-2-alkylaminosulphonyl or di-(C_1-2-alkyl)aminosulphonyl group,
- and R¹¹and R¹², which may be identical or different, denote a hydrogen, fluorine, chlorine or bromine atom or
- a methyl, cyano, trifluoromethyl or methoxy group,
- or, R¹¹together with R¹², if they are bound to adjacent carbon atoms, also denote a methylenedioxy, difluoromethylenedioxy, 1,3-propylene or 1,4-butylene group,

a phenyl-C_1-3-alkyl group wherein the alkyl moiety is substituted by a carboxy, C_1-2-alkyloxy-carbonyl, aminocarbonyl, C_1-2-alkylaminocarbonyl or di-(C_1-2-alkylamino-carbonyl group,

a phenyl-C_2-3-alkenyl group, wherein the phenyl moiety may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl or methoxy group,

a phenyl-(CH₂)_m-A-(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined and

- A denotes a carbonyl, hydroxyiminomethylene or C_1-2-alkyloxyiminomethylene group, m denotes the number 0 or 1 and n denotes the number 1 or 2,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹², m and n are as hereinbefore defined and

- B denotes a methylene group which is substituted by a hydroxy or C_1-2-alkyloxy group and is optionally additionally substituted by a methyl group,

a naphthylmethyl or naphthylethyl group, wherein the naphthyl moiety is substituted in each case by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined,

a [1,4]naphthoquinon-2-yl, chromen-4-on-3-yl or 1-oxoindan-2-yl group,

a heteroaryl-C_1-3-alkyl group, wherein by the term heteroaryl is meant a pyrrolyl, imidazolyl, triazolyl, furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolyl, benzimidazolyl, 2,3-dihydro-2-oxo-1H-benzimidazolyl, indazolyl, benzofuranyl, 2,3-dihydrobenzofuranyl, benzoxazolyl, dihydro-2-oxo-benzoxazolyl, benzisoxazolyl, benzothiophenyl, benzothiazolyl, benzoisothiazolyl, quinolinyl, 1,2-dihydro-2-oxo-quinolinyl, isoquinolinyl, 1,2-dihydro-1-oxo-isoquinolinyl, cinnolinyl, quinazolinyl, 1,2-dihydro-2-oxo-quinazolinyl, 1,2-dihydro-1-oxo-phthalazin-4-yl, cumarinyl or 3,4-dihydro-3-oxo-2H-benzo[1,4]oxazinyl group,

- wherein the abovementioned heteroaryl groups may be substituted at carbon atoms by a fluorine, chlorine or bromine atom, by a methyl, trifluoromethyl, cyano, aminocarbonyl, aminosulphonyl, methylsulphonyl, nitro, amino, acetylamino, methylsulphonylamino, methoxy, difluoromethoxy or trifluoromethoxy group and the imino groups of the abovementioned heteroaryl groups may be substituted by methyl or ethyl groups,

a furanyl-A-CH₂, thienyl-A-CH₂, thiazolyl-A-CH₂or pyridyl-A-CH₂group, wherein A is as hereinbefore defined,

a furanyl-Bâ€”CH₂, thienyl-Bâ€”CH₂, thiazolyl-Bâ€”CH₂or pyridyl-Bâ€”CH₂group, wherein B is as hereinbefore defined,

a C_1-4-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-6-cycloalkyl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a C_3-6-cycloalkyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

an R²¹-A-(CH₂)_ngroup wherein R²¹denotes a C_1-2-alkyloxycarbonyl, aminocarbonyl, C_1-2-alkylaminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl or morpholin-4-yl-carbonyl group and A and n are as hereinbefore defined,

a C_1-4-alkyl group substituted by a group R_a, wherein

- R_adenotes a cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group,

a C_2-4-alkyl group substituted by a group R_b, wherein

- R_bdenotes a hydroxy, C_1-3-alkyloxy, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl, 4-methyl-piperazin-1-yl or 4-ethyl-piperazin-1-yl group and is isolated by at least two carbon atoms from the cyclic nitrogen atom in the 1 position of the xanthine skeleton,

or an amino or benzoylamino group,

R²denotes a hydrogen atom,

a C_1-6-alkyl group,

a C_2-4-alkenyl group,

a C_3-4-alkynyl group,

a C_3-6-cycloalkyl group,

a C_3-6-cycloalkyl-C_1-3-alkyl group,

a tetrahydrofuran-3-yl, tetrahydropyran-3-yl, tetrahydropyran-4-yl, tetrahydrofuranylmethyl or tetrahydropyranylmethyl group,

a phenyl group which is optionally substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,

a phenyl-C_2-3-alkenyl group, wherein the phenyl moiety may be substituted by a fluorine, chlorine or bromine atom or by a methyl, trifluoromethyl or methoxy group,

a heteroaryl-C_1-3-alkyl group, wherein the term heteroaryl is as hereinbefore defined,

a furanylcarbonylmethyl, thienylcarbonylmethyl, thiazolylcarbonylmethyl or pyridylcarbonylmethyl group,

a C_1-4-alkyl-carbonyl-C_1-2-alkyl group,

a C_3-6-cycloalkyl-carbonyl-C_1-2-alkyl group,

a C_1-4-alkyl group substituted by a group R_a, wherein R_ais as hereinbefore defined,

a C_2-4-alkyl group substituted by a group R_b, wherein R_bis as hereinbefore defined and is isolated by at least two carbon atoms from the cyclic nitrogen atom in the 3 position of the xanthine skeleton,

R³denotes a C_2-6-alkyl group,

a C_3-7-alkenyl group,

a C_3-5-alkenyl group which is substituted by a fluorine, chlorine or bromine atom or a trifluoromethyl group,

a C_3-6-alkynyl group,

a C_1-3-alkyl group substituted by the group R_c, wherein

- R_cdenotes a C_3-6-cycloalkyl group optionally substituted by one or two methyl groups,
- a C_5-6-cycloalkenyl group optionally substituted by one or two methyl groups,
- a phenyl group optionally substituted by a fluorine, chlorine, bromine or iodine atom, by a methyl, trifluoromethyl, cyano, nitro, amino, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,
- a phenyl group which is substituted by two fluorine atoms,
- a naphthyl group or
- a furanyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl or pyridyl group optionally substituted by a methyl or trifluoromethyl group,

a phenyl group optionally substituted by a fluorine, chlorine or bromine atom, by a methyl, trifluoromethyl, cyano, hydroxy, methoxy, difluoromethoxy or trifluoromethoxy group,

a phenyl group which is substituted by two methyl groups,

a naphthyl group

or a phenyl-C_2-3-alkenyl group

and

R⁴denotes a pyrrolidin-1-yl group which is substituted in the 3 position by an amino, methylamino or dimethylamino group,

an azetidin-1-yl group which is substituted by an aminomethyl group,

a pyrrolidin-1-yl group which is substituted by an aminomethyl group,

a piperidin-1-yl group which is substituted in the 3 position or in the 4 position by an amino, methylamino, dimethylamino or [(2-cyano-pyrrolidin-1-yl-)carbonylmethyl]-amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl or ethyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety in the 4 position or in the 5 position is additionally substituted by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein the methylene group in the 2 position or in the 6 position is replaced by a carbonyl group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂â€” bridge,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 6 position is replaced by a â€”CH₂â€”CH₂â€” bridge,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 4 position together with a hydrogen atom in the 6 position is replaced by a â€”CH₂â€”CH₂â€”bridge,

a piperidin-1-yl group which is substituted by an aminomethyl group,

a piperidin-3-yl or piperidin-4-yl group,

a piperidin-3-yl or piperidin-4-yl group which is substituted in the 1 position by an amino group,

a hexahydroazepin-1-yl group which is substituted in the 3 position or in the 4 position by an amino group,

a piperazin-1-yl or [1,4]diazepan-1-yl group optionally substituted at the carbon skeleton by one or two methyl groups,

a 3-imino-piperazin-1-yl, 3-imino-[1,4]diazepan-1-yl or 5-imino-[1,4]diazepan-1-yl group,

a [1,4]diazepan-1-yl group, which is substituted in the 6 position by an amino group,

a C_3-6-cycloalkyl-amino group wherein the cycloalkyl moiety is substituted by an amino, methylamino or dimethylamino group, wherein the two nitrogen atoms are isolated from one another at the cycloalkyl moiety by at least two carbon atoms,

an Nâ€”(C_3-6-cycloalkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, methylamino or dimethylamino group, wherein the two nitrogen atoms are isolated from one another at the cycloalkyl moiety by at least two carbon atoms,

a C_3-6-cycloalkyl-amino group wherein the cycloalkyl moiety is substituted by an aminomethyl or aminoethyl group,

an Nâ€”(C_3-6-cycloalkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an aminomethyl or aminoethyl group,

a C_3-6-cycloalkyl-C_1-2-alkyl-amino group wherein the cycloalkyl moiety is substituted by an amino, aminomethyl or aminoethyl group,

an Nâ€”(C_3-6-cycloalkyl-C_1-2-alkyl)-Nâ€”(C_1-2-alkyl)-amino group wherein the cycloalkyl moiety is substituted by an amino, aminomethyl or aminoethyl group,

an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a C_1-4-alkyl group and
- R¹⁶denotes a 2-aminoethyl, 2-(methylamino)ethyl or 2-(dimethylamino)ethyl group, wherein the ethyl moiety may in each case be substituted by one or two methyl or ethyl groups or by an aminocarbonyl, C_1-2-alkyl-aminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group,

an amino group wherein the nitrogen atom is substituted by a pyrrolidin-3-yl, piperidin-3-yl, piperidin-4-yl, pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-2-ylmethyl, piperidin-3-ylmethyl or piperidin-4-ylmethyl group,

a C_1-2-alkylamino group wherein the nitrogen atom is substituted by a pyrrolidin-3-yl, piperidin-3-yl, piperidin-4-yl, pyrrolidin-2-ylmethyl, pyrrolidin-3-ylmethyl, piperidin-2-ylmethyl, piperidin-3-ylmethyl or piperidin-4-ylmethyl group,

a 3-amino-propyl, 3-methylamino-propyl or 3-dimethylamino-propyl group wherein the propyl moiety may be substituted by one or two methyl groups,

a 4-amino-butyl, 4-methylamino-butyl or 4-dimethylamino-butyl group wherein the butyl moiety may be substituted by one or two methyl groups,

a C_1-2-alkyl group which is substituted by a 2-pyrrolidinyl, 3-pyrrolidinyl, 2-piperidinyl, 3-piperidinyl or 4-piperidinyl group,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

a C_3-6-cycloalkyl group which is substituted by an amino, aminomethyl or aminoethyl group or

a C_3-6-cycloalkyl-C_1-2-alkyl group wherein the cycloalkyl moiety is substituted by an amino, aminomethyl or aminoethyl group,

while, unless otherwise stated, the abovementioned alkyl, alkenyl and alkynyl groups may be straight-chain or branched,

with the proviso that the compounds wherein

R¹denotes a hydrogen atom, a methyl, propyl, 2-hydroxypropyl, aminocarbonyl-methyl or benzyl group,

R²denotes a methyl group,

R³denotes a C_1-5-alkyl group, a benzyl group optionally substituted by a fluorine, chlorine or bromine atom or by a methyl group, a 1-phenylethyl or 2-phenylethyl group, a 2-propen-1-yl, 2-buten-1-yl, 3-chloro-2-buten-1-yl or 2-methyl-2-propen-1-yl group

and

R⁴denotes a piperazin-1-yl group, are excluded,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A sub-group of the preferred compounds of formula I deserving special mention relates to those compounds of general formula I wherein R¹to R⁴are as hereinbefore defined, with the additional proviso that the compounds wherein R⁴denotes an optionally substituted piperazin-1-yl or [1,4]diazepan-1-yl group are excluded, the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A second sub-group of the preferred compounds of formula I deserving special mention relates to those compounds of general formula I wherein

R¹denotes a hydrogen atom,

a C_1-4-alkyl group,

a C_3-5-alkenyl group,

a 2-propen-1-yl group which is substituted by a methoxycarbonyl group,

a C_3-5-alkynyl group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein

- R¹⁰denotes a hydrogen atom, a fluorine, chlorine or bromine atom,
- a methyl, ethyl, trifluoromethyl or ethynyl group,
- a hydroxy, methoxy, ethoxy, difluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, phenoxy, benzyloxy, 2-propen-1-yloxy, 2-propyn-1-yloxy, cyano-C_1-2-alkyloxy, C_1-2-alkyl-sulphonyloxy, phenylsulphonyloxy, carboxy-C_1-2alkyloxy, C_1-2-alkyloxy-carbonyl-C_1-2-alkyloxy, am inocarbonyl-C_1-2-alkyloxy, C_1-2-alkyl-aminocarbonyl-C_1-2-alkyloxy, di-(C_1-2-alkyl)aminocarbonyl-C_1-2-alkyloxy, pyrrolidin-1-ylcarbonyl-C_1-2-alkyloxy, piperidin-1-ylcarbonyl-C_1-2-alkyloxy, morpholin-4-ylcarbonyl-C_1-2-alkyloxy group,
- a carboxy, C,_â€”2-alkyloxy-carbonyl, aminocarbonyl, C_i-ralkylaminocarbonyl, di-(C_1-2-alkyl)aminocarbonyl, morpholin-4-ylcarbonyl or cyano group,
- a nitro, amino, C_1-2-alkylamino, di-(C_1-2-alkyl)amino, cyano-C_1-2-alkylamino, [N-(cyano-C_1-2-alkyl)-N-methyl-amino], C_1-2-alkyloxy-carbonyl-C_1-2-alkylamino, C_1-2-alkyl-carbonylamino, C_1-2-alkyloxy-carbonylamino, C_1-2-alkylsulphonylamino, bis-(C_1-2-alkylsulphonyl)-amino, aminosulphonylamino, C_1-2-alkylamino-sulphonylamino, di-(C_1-2-alkyl)amino-sulphonylamino, morpholin-4-yl-sulphonylamino, (C_1-2-alkylamino)thiocarbonylamino, (C_1-2-alkyloxy-carbonylamino)carbonylamino, aminocarbonylamino, C_1-2-alkylaminocarbonylamino, di-(C_1-2-alkyl)aminocarbonylamino or morpholin-4-yl-carbonylamino group,
- a 2-oxo-imidazolidin-1-yl, 3-methyl-2-oxo-imidazolidin-1-yl, 2,4-dioxo-imidazolidin-1-yl, 3-methyl-2,4-dioxo-imidazolidin-1-yl, 2,5-dioxo-imidazolidin-1-yl, 3-methyl-2,5-dioxo-imidazolidin-1-yl, 2-oxo-hexahydropyrimidin-1-yl or 3-methyl-2-oxo-hexahydropyrimidin-1-yl group,
- or
- a C_1-2-alkylsulphanyl, C_1-2-alkylsulphinyl, C_1-2-alkylsulphonyl, aminosulphonyl,

C_1-2-alkylaminosulphonyl or di-(C_1-2-alkyl)aminosulphonyl group,

- and R¹¹and R¹², which may be identical or different, denote a hydrogen, fluorine, chlorine or bromine atom or
- a methyl, cyano or methoxy group,
- or, R¹¹together with R¹², if they are bound to adjacent carbon atoms, also denote a methylenedioxy group,

a phenylmethyl group wherein the methyl moiety is substituted by a carboxy, methoxycarbonyl or aminocarbonyl group,

a 2-phenylethyl group wherein the ethyl moiety is substituted by a carboxy, methoxycarbonyl or aminocarbonyl group,

a 2-phenylethyl group wherein the ethyl moiety is substituted in the 2 position by a hydroxy, methoxy, hydroxyimino or methoxyimino group,

a 2-phenylethyl group wherein the ethyl moiety is substituted in the 2 position by a hydroxy group and a methyl group,

a phenylcarbonylmethyl group wherein the phenyl moiety is substituted by R¹⁰to R¹², wherein R¹⁰to R¹²are as hereinbefore defined,

a 1-(phenylcarbonyl)ethyl or 2-(phenylcarbonyl)ethyl group,

a 2-phenylethenyl group,

a phenylsulphanylmethyl or phenylsulphinylmethyl group,

a 2-(phenyloxy)ethyl group,

a naphthylmethyl or naphthylethyl group, wherein the naphthyl moiety may be substituted in each case by a methyl, nitro, amino, acetylamino, methylsulphonylamino, cyano, aminocarbonyl or aminosulphonyl group,

a [1,4]naphthoquinon-2-yl, chromen-4-on-3-yl or 1-oxoindan-2-yl group

an oxazolylmethyl, isoxazolylmethyl, thiazolylmethyl, pyridylmethyl, benzofuranylmethyl, 2,3-dihydrobenzofuranylmethyl, benzo[d]isoxazolylmethyl, benzo-[d]isothiazolylmethyl, (1 H-indazol-3-yl)methyl, quinolinylmethyl, (1,2-dihydro-2-oxo-quinolin-4-yl)methyl, isoquinolinylmethyl, (1,2-dihydro-1-oxo-isoquinolin-4-yl)methyl, cinnolinylmethyl, quinazolinylmethyl, (1,2-dihydro-2-oxo-quinazolin-4-yl)methyl, (1,2-dihydro-1-oxo-phthalazin-4-yl)methyl or cumarinylmethyl group, wherein the heterocyclic moiety may be substituted by a methyl group in each case,

a quinolinylmethyl or isoquinolinylmethyl group, wherein the heterocyclic moiety is substituted in each case by a cyano, nitro, amino, acetylamino, methylsulphonylamino, aminocarbonyl or aminosulphonyl group,

a pyrrolylethyl, triazolylethyl, thienylethyl, thiazolylethyl or pyridylethyl group, wherein the heterocyclic moiety may be substituted in each case by a methyl group,

a furanylcarbonylmethyl, thienylcarbonylmethyl, thiazolylcarbonylmethyl or pyridylcarbonylmethyl group,

a methyl group which is substituted by a cyclopropyl, cyano, carboxy, aminocarbonyl or methoxycarbonyl group,

an ethyl group which is substituted in the 2 position by a hydroxy, methoxy, dimethylamino, carboxy or methoxycarbonyl group, or

a propyl group which is substituted in the 3 position by a hydroxy, dimethylamino, carboxy or methoxycarbonyl group,

a 2-oxopropyl group or

an amino or benzoylamino group,

R²denotes a hydrogen atom,

a C_1-6-alkyl group,

an ethenyl group,

a 2-propen-1-yl or 2-propyn-1-yl group,

a C_3-6-cycloalkyl group,

a tetrahydrofuran-3-yl, tetrahydropyran-3-yl, tetrahydropyran-4-yl, tetrahydro-furanylmethyl or tetrahydropyranylmethyl group,

a phenyl group,

a phenyl-C_1-4-alkyl group, wherein the phenyl moiety may be substituted by a fluorine or chlorine atom, a methyl, dimethylamino, hydroxy, methoxy or trifluoromethoxy group,

a phenylcarbonylmethyl group, wherein the phenyl moiety may be substituted by a fluorine or chlorine atom, a hydroxy, methoxy or trifluoromethoxy group,

a 2-phenylethenyl group,

a 2-(phenyloxy)ethyl group,

a pyridylmethyl or pyridylethyl group,

a methyl group which is substituted by a C_3-6-cycloalkyl, cyano, carboxy or methoxy-carbonyl group, or

an ethyl group which is substituted in the 2 position by a C_3-6-cycloalkyl, cyano, carboxy, methoxycarbonyl, hydroxy, methoxy or dimethylamino group,

or a propyl group which is substituted in the 3 position by a C_3-6-cycloalkyl, cyano, carboxy, methoxycarbonyl, hydroxy, methoxy or dimethylamino group,

R³denotes a C_4-6-alkenyl group,

a 1-cyclopenten-1-ylmethyl or 1-cyclohexen-1-ylmethyl group,

a 1-cyclopenten-1-ylmethyl group wherein the 1-cyclopenten-1-yl moiety is substituted by a methyl group,

a 2-propyn-1-yl, 2-butyn-1-yl or 2-pentyn-1-yl group,

a phenyl group which may be substituted by a fluorine atom or a cyano, methyl-methoxy or trifluoromethyl group,

a phenyl group which is substituted by two methyl groups,

a benzyl group wherein the phenyl moiety may be substituted by one or two fluorine atoms, a chlorine, bromine or iodine atom, or a methyl, methoxy, cyano, nitro or amino group,

a furanylmethyl or thienylmethyl group,

a cyclopropylmethyl group or

a cyclopropylmethyl group wherein the cyclopropyl moiety is substituted by a methyl group, and

R⁴denotes a piperidin-1-yl group which is substituted in the 3 position by an amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl, pyrrolidin-1-yl-carbonyl, (2-cyano-pyrrolidin-1-yl-)carbonyl, thiazolidin-3-yl-carbonyl, (4-cyano-thiazolidin-3-yl)carbonyl, piperidin-1-ylcarbonyl or morpholin-4-ylcarbonyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety in the 4 position or in the 5 position is additionally substituted by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂-bridge,

a hexahydroazepin-1-yl group which is substituted in the 3 position by an amino group,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

a [1,4]diazepan-1-yl group, which is substituted in the 6 position by an amino group,

a cyclohexyl group which is substituted in the 3 position by an amino group,

a 2-amino-cyclohexylamino group,

or an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a methyl or ethyl group and
- R¹⁶denotes a 2-aminoethyl group, wherein the ethyl moiety may be substituted by one or two methyl groups or by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl or pyrrolidin-1-ylcarbonyl group,

unless otherwise stated, the abovementioned alkyl and alkenyl groups may be straight-chained or branched,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A third sub-group of the preferred compounds of formula I deserving special mention relates to those compounds of general formula I wherein R¹, R²and R³are as hereinbefore defined and

R⁴denotes a piperidin-1-yl group which is substituted in the 3 position by an amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted in the 4 position or in the 5 position by a hydroxy or methoxy group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂-bridge,

a hexahydroazepin-1-yl group which is substituted in the 3 position by an amino group,

a 3-amino-2-oxo-piperidin-5-yl or 3-amino-2-oxo-1-methyl-piperidin-5-yl group,

a cyclohexyl group which is substituted in the 3 position by an amino group,

a 2-amino-cyclohexylamino group,

or an amino group substituted by the groups R¹⁵and R¹⁶, wherein

- R¹⁵denotes a methyl or ethyl group and
- R¹⁶denotes a 2-aminoethyl group, wherein the ethyl moiety may be substituted by one or two methyl groups or by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl or pyrrolidin-1-ylcarbonyl group,

unless otherwise stated, the abovementioned alkyl- and alkenyl groups may be straight-chained or branched,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

Particularly preferred compounds of the above general formula I are those wherein

R¹denotes a hydrogen atom,

a C_1-4-alkyl group,

a C_3-5-alkenyl group,

a 2-propen-1-yl group which is substituted by a methoxycarbonyl group,

a C_3-5-alkynyl group,

a phenyl group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety may be substituted by one or two fluorine atoms, one or two chlorine atoms, a bromine atom, one to three methyl groups, a butyl, trifluoromethyl, hydroxy, methoxy, nitro, amino, carboxy or ethoxycarbonyl group,

a 2-phenylethyl group wherein the ethyl moiety is substituted in the 2 position by a hydroxy, methoxy or hydroxyimino group,

a phenylcarbonylmethyl group wherein the phenyl moiety may be substituted by a fluorine atom or by a methyl, aminocarbonyl, aminosulphonyl, cyano, hydroxy, methoxy, phenoxy, benzyloxy, 2-propen-1-yloxy, 2-propyn-1-yloxy, cyanomethoxy, (methoxycarbonyl)methoxy, (aminocarbonyl)methoxy, (methylaminocarbonyl)-methoxy, (dimethylaminocarbonyl)methoxy, methylsulphonyloxy, phenylsulphonyloxy, nitro, amino, (methoxycarbonyl)methylamino, acetylamino, methoxycarbonylamino, methylsulphonylamino, bis-(methylsulphonyl)-amino, aminocarbonylamino, dimethylaminocarbonylamino, (methylamino)thiocarbonylamino, (ethoxy carbonylamino)carbonylamino or cyanomethylamino group,

a phenylcarbonylmethyl group wherein the phenyl moiety is substituted by two methoxy groups or by a bromine atom and by a dimethylamino group,

a 2-(phenylcarbonyl)ethyl group,

a 2-phenylethenyl group,

a 2-(phenoxy)ethyl group,

a phenylsulphanylmethyl or phenylsulphinylmethyl group,

a naphthylmethyl or naphthylethyl group,

an isoxazolylmethyl, thiazolylmethyl, pyridylmethyl, benzo[d]isoxazolylmethyl, benzo[d]isothiazolylmethyl, (1 H-indazol-3-yl)methyl, quinolinylmethyl or isoquinolinylmethyl group, wherein the heterocyclic moiety may in each case be substituted by a methyl group,

a isoquinolinylmethyl group wherein the isoquinolinyl moiety is substituted by a nitro or amino group,

a (1,2-dihydro-2-oxo-quinolin-4-yl)methyl group,

a chromen-4-on-3-yl group,

a pyrrolylethyl, triazolylethyl, thienylethyl, thiazolylethyl or pyridylethyl group, wherein the heterocyclic moiety may in each case be substituted by a methyl group,

a thienylcarbonylmethyl group,

a methyl group which is substituted by a cyclopropyl, cyano, carboxy, aminocarbonyl or methoxycarbonyl group,

an ethyl group which is substituted in the 2 position by a hydroxy, methoxy, dimethylamino, carboxy or methoxycarbonyl group, or

a propyl group which is substituted in the 3 position by a hydroxy, dimethylamino, carboxy or methoxycarbonyl group,

a 2-oxopropyl group or

an amino or benzoylamino group,

R²denotes a hydrogen atom,

a C_1-6-alkyl group,

an ethenyl group,

a 2-propen-1-yl or 2-propyn-1-yl group,

a phenyl group,

a phenyl-C_1-4-alkyl group, wherein the phenyl moiety may be substituted by a fluorine atom, a methyl or methoxy group,

a phenylcarbonylmethyl group,

a 2-phenylethenyl group,

a methyl group which is substituted by a cyclopropyl, cyano, carboxy or methoxy-carbonyl group, or

an ethyl group which is substituted in the 2 position by a cyano, hydroxy, methoxy or dimethylamino group,

R³denotes a C_4-6-alkenyl group,

a 1-cyclopenten-1-ylmethyl or 1-cyclohexen-1-ylmethyl group,

a 2-propyn-1-yl, 2-butyn-1-yl or 2-pentyn-1-yl group,

a phenyl group which may be substituted by a fluorine atom or a cyano, methyl or trifluoromethyl group,

a phenyl group which is substituted by two methyl groups,

a naphthyl group,

a benzyl group wherein the phenyl moiety may be substituted by one or two fluorine atoms, an iodine atom or a cyano, nitro or amino group,

a naphthylmethyl group,

a 2-phenylethenyl group,

a furanylmethyl or thienylmethyl group or

a cyclopropylmethyl group and

R⁴denotes a pyrrolidin-1-yl group which is substituted in the 3 position by an amino group,

an azetidin-1-yl group which is substituted by an aminomethyl group,

a pyrrolidin-1-yl group which is substituted by an aminomethyl group,

a piperidin-1-yl group which is substituted in the 3 position or in the 4 position by an amino, methylamino, dimethylamino or [(2-cyano-pyrrolidin-1-yl)carbonylmethyl]-amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted by a pyrrolidin-1-yl-carbonyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety in the 4 position is additionally substituted by a hydroxy group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂-bridge,

a piperidin-1-yl group which is substituted by an aminomethyl group,

a piperidin-3-yl or piperidin-4-yl group,

a 1-amino-piperidin-3-yl or 1-amino-piperidin-4-yl group,

a hexahydroazepin-1-yl group which is substituted in the 3 position or in the 4 position by an amino group,

a piperazin-1-yl or [1,4]diazepan-1-yl group,

a [1,4]diazepan-1-yl group, which is substituted in the 6 position by an amino group,

a 3-aminopropyl group,

a cyclohexyl group which is substituted by an amino group,

a 2-amino-cyclopropylamino group,

a 2-amino-cyclobutylamino group,

a 2-amino-cyclopentylamino or 3-amino-cyclopentylamino group,

a 2-amino-cyclohexylamino, 2-(methylamino)-cyclohexylamino or 3-amino-cyclohexylamino group,

an N-(2-aminocyclohexyl)-methylamino group,

an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a methyl or ethyl group and
- R¹⁶denotes a 2-aminoethyl-2-(methylamino)ethyl or 2-(dimethylamino)ethyl group, wherein the ethyl moiety may be substituted by one or two methyl groups or by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl or pyrrolidin-1-ylcarbonyl group,

or an amino or methylamino group wherein the nitrogen atom is substituted by a pyrrolidin-3-yl, piperidin-3-yl, piperidin-4-yl or piperidin-2-ylmethyl group,

while unless otherwise stated, the abovementioned alkyl and alkenyl groups may be straight-chain or branched,

with the proviso that the compounds

3-methyl-7-(2-buten-1-yl)-8-(piperazin-1-yl)-xanthine,

3-methyl-7-(2-methyl-2-propen-1-yl)-8-(piperazin-1-yl)-xanthine,

3-methyl-7-benzyl-8-(piperazin-1-yl)-xanthine,

1,7-dibenzyl-3-methyl-8-(piperazin-1-yl)-xanthine and

1,3-dimethyl-7-(4-fluorobenzyl)-8-(piperazin-1-yl)-xanthine

are excluded,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A sub-group of the particularly preferred compounds of formula I deserving special mention relates to those compounds of general formula I wherein R¹to R⁴are as hereinbefore defined, with the additional proviso that the compounds wherein R⁴denotes an optionally substituted piperazin-1-yl or [1,4]diazepan-1-yl group are excluded, the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A second sub-group of the particularly preferred compounds of formula I deserving special mention relates to those compounds of general formula I wherein

R¹denotes a hydrogen atom,

a C_1-4-alkyl group,

a C_3-5-alkenyl group,

a 2-propen-1-yl group which is substituted by a methoxycarbonyl group,

a C_3-5-alkynyl group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety may be substituted by one or two fluorine atoms, one or two chlorine atoms, a bromine atom, one to three methyl groups, a trifluoromethyl, hydroxy, methoxy, nitro, amino, carboxy or ethoxycarbonyl group,

a 2-phenylethyl group wherein the ethyl moiety is substituted in the 2 position by a hydroxy, methoxy or hydroxyimino group,

a phenylcarbonylmethyl group wherein the phenyl moiety may be substituted by a fluorine atom or by a methyl, aminocarbonyl, aminosulphonyl, cyano, hydroxy, methoxy, phenoxy, benzyloxy, 2-propen-1-yloxy, 2-propyn-1-yloxy, cyanomethoxy, (methoxycarbonyl)methoxy, (aminocarbonyl)methoxy, (methylaminocarbonyl)-methoxy, (dimethylaminocarbonyl)methoxy, methylsulphonyloxy, phenylsulphonyloxy, nitro, amino, (methoxycarbonyl)methylamino, acetylamino, methoxycarbonylamino, methylsulphonylamino, bis-(methylsulphonyl)-amino, aminocarbonylamino, dimethylaminocarbonylamino, (methylamino)thiocarbonylamino, (ethoxycarbonylamino)carbonylamino or cyanomethylamino group,

a phenylcarbonylmethyl group wherein the phenyl moiety is substituted by two methoxy groups or by a bromine atom and by a dimethylamino group,

a 2-(phenylcarbonyl)ethyl group,

a 2-phenylethenyl group,

a 2-(phenoxy)ethyl group,

a phenylsulphanylmethyl or phenylsulphinylmethyl group,

a naphthylmethyl or naphthylethyl group,

an isoquinolinylmethyl group wherein the isoquinolinyl moiety is substituted by a nitro or amino group,

a (1,2-dihydro-2-oxo-quinolin-4-yl)methyl group,

a pyrrolylethyl, triazolylethyl, thienylethyl, thiazolylethyl or pyridylethyl group, wherein the heterocyclic moiety may be substituted in each case by a methyl group,

a thienylcarbonylmethyl group,

a methyl group which is substituted by a cyclopropyl, cyano, carboxy, aminocarbonyl or methoxycarbonyl group,

an ethyl group which is substituted in the 2 position by a hydroxy, methoxy, dimethylamino, carboxy or methoxycarbonyl group, or

a propyl group which is substituted in the 3 position by a hydroxy, dimethylamino, carboxy or methoxycarbonyl group,

a 2-oxopropyl group or

an amino or benzoylamino group,

R²denotes a hydrogen atom,

a C_1-6-alkyl group,

an ethenyl group,

a 2-propen-1-yl or 2-propyn-1-yl group,

a phenyl group,

a phenyl-C_1-4-alkyl group wherein the phenyl moiety may be substituted by a fluorine atom, a methyl or methoxy group,

a phenylcarbonylmethyl group,

a 2-phenylethenyl group,

a methyl group which is substituted by a cyclopropyl, cyano, carboxy or methoxy-carbonyl group, or

an ethyl group which is substituted in the 2 position by a cyano, hydroxy, methoxy or dimethylamino group, p R³denotes a C_4-6-alkenyl group,

a 1-cyclopenten-1-ylmethyl or 1-cyclohexen-1-ylmethyl group,

a 2-propyn-1-yl, 2-butyn-1-yl or 2-pentyn-1-yl group,

a phenyl group which may be substituted by a fluorine atom or a cyano, methyl or trifluoromethyl group,

a phenyl group which is substituted by two methyl groups,

a benzyl group wherein the phenyl moiety may be substituted by one or two fluorine atoms, an iodine atom or a cyano, nitro or amino group,

a furanylmethyl or thienylmethyl group or

a cyclopropylmethyl group and

R⁴denotes a piperidin-1-yl group which is substituted in the 3 position by an amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted by a pyrrolidin-1-yl-carbonyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted in the 4 position by a hydroxy group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂-bridge,

a hexahydroazepin-1-yl group which is substituted in the 3 position by an amino group,

a [1,4]diazepan-1-yl group, which is substituted in the 6 position by an amino group,

a cyclohexyl group which is substituted in the 3 position by an amino group,

a 2-amino-cyclohexylamino group,

or an amino group substituted by the groups R¹⁵and R¹⁶wherein

- R¹⁵denotes a methyl or ethyl group and
- R¹⁶denotes a 2-aminoethyl group, wherein the ethyl moiety may be substituted by one or two methyl groups or by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl or pyrrolidin-1-ylcarbonyl group,

unless otherwise stated, the abovementioned alkyl and alkenyl groups may be straight-chained or branched,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

A third sub-group of the particularly preferred compounds of formula I deserving special mention comprises those compounds of general formula I wherein

R¹, R²and R³are as hereinbefore defined and

R⁴denotes a piperidin-1-yl group which is substituted in the 3 position by an amino group, wherein the piperidin-1-yl moiety may additionally be substituted by a methyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety is additionally substituted by a pyrrolidin-1-yl-carbonyl group,

a 3-amino-piperidin-1-yl group wherein the piperidin-1-yl moiety in the 4 position is additionally substituted by a hydroxy group,

a 3-amino-piperidin-1-yl group wherein a hydrogen atom in the 2 position together with a hydrogen atom in the 5 position is replaced by a â€”CH₂â€”CH₂-bridge,

a hexahydroazepin-1-yl group which is substituted in the 3 position by an amino group,

a cyclohexyl group which is substituted in the 3 position by an amino group,

a 2-amino-cyclohexylamino group,

or an amino group substituted by the groups R¹⁵and R¹⁶, wherein

- R¹⁵denotes a methyl or ethyl group and
- R¹⁶denotes a 2-aminoethyl group, wherein the ethyl moiety may be substituted by one or two methyl groups or by an aminocarbonyl, methylaminocarbonyl, dimethylaminocarbonyl or pyrrolidin-1-ylcarbonyl group,

unless otherwise stated, the abovementioned alkyl- and alkenyl groups may be straight-chained or branched,

the tautomers, enantiomers, diastereomers, mixtures thereof and the salts thereof.

Another sub-group of compounds of general formula I which should be mentioned comprises those compounds wherein

R¹denotes a hydrogen atom,

a C_1-8-alkyl group,

a C_3-8-alkynyl group,

a C_1-6-alkyl group substituted by a group R_a, wherein

- R_adenotes a C_3-7-cycloalkyl, heteroaryl, cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkylamino-carbonyl, di-(C_1-3-alkyl)-amino-carbonyl, pyrrolidin-1-ylcarbonyl, piperidin-1-ylcarbonyl, morpholin-4-ylcarbonyl, piperazin-1-ylcarbonyl, 4-methylpiperazin-1-ylcarbonyl or 4-ethylpiperazin-1-ylcarbonyl group,

a C_1-6-alkyl group substituted by a phenyl group, wherein the phenyl ring is substituted by the groups R¹⁰to R¹⁴and

- R¹⁰denotes a hydrogen atom,
- a fluorine, chlorine, bromine or iodine atom,
- a C_1-4-alkyl, hydroxy, or C_1-4-alkyloxy group,
- a nitro, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl, 4-(C_1-3-alkyl)-piperazin-1-yl, C_1-3-alkyl-carbonylamino, arylcarbonylamino, aryl-C_1-3-alkyl-carbonylamino, C_1-3-alkyloxy-carbonylamino, aminocarbonylamino, C_1-3-alkyl-aminocarbonylamino,
- di-(C_1-3-alkyl)aminocarbonylamino, C_1-3-alkyl-sulphonylamino, arylsulphonylamino or aryl-C_1-3-alkyl-sulphonylamino group,
- an Nâ€”(C_1-3-alkyl)-C_1-3-alkyl-carbonylamino, Nâ€”(C_1-3-alkyl)-arylcarbonylamino, Nâ€”(C_1-3-alkyl)-aryl-C_1-3-alkyl-carbonylamino, Nâ€”(C_1-3-alkyl)-C_1-3-alkyloxy-carbonylamino, N-(aminocarbonyl)-C_1-3-alkylamino, Nâ€”(C_1-3-alkyl-aminocarbonyl)-C_1-3-alkylamino, N-[di-(C_1-3-alkyl)aminocarbonyl]-C_1-3-alkylamino, Nâ€”(C_1-3-alkyl)-C_1-3-alkyl-sulphonylamino, Nâ€”(C_1-3-alkyl)-arylsulphonylamino or Nâ€”(C_1-3-alkyl)-aryl-C_1-3-alkyl-sulphonylamino group,
- a cyano, carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkyl-aminocarbonyl, di-(C_1-3-alkyl)-aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl, morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonyl group,
- a C_1-3-alkyl-carbonyl or an arylcarbonyl group,
- a carboxy-C_1-3-alkyl, C_1-3-alkyloxy-carbonyl-C_1-3-alkyl, cyano-C_1-3-alkyl, aminocarbonyl-C_1-3-alkyl, C_1-3-alkyl-aminocarbonyl-C_1-3-alkyl, di-(C_1-3-alkyl)-aminocarbonyl-C_1-3-alkyl, pyrrolidin-1-yl-carbonyl-C_1-3-alkyl, piperidin-1-yl-carbonyl-C_1-3-alkyl, morpholin-4-yl-carbonyl-C_1-3-alkyl, piperazin-1-yl-carbonyl-C_1-3-alkyl or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonyl-C_1-3-alkyl group,
- a carboxy-C_1-3-alkyloxy, C,_â€”3-alkyloxy-carbonyl-C_1-3-alkyloxy, cyano-C_1-3-alkyloxy, aminocarbonyl-C_1-3-alkyloxy, C,_â€”3-alkyl-aminocarbonyl-C_1-3-alkyloxy, di-(C_1-3-alkyl)-aminocarbonyl-C_1-3-alkyloxy, pyrrolidin-1-yl-carbonyl-C_1-3-alkyl-oxy, piperidin-1-yl-carbonyl-C_1-3-alkyloxy, morpholin-4-yl-carbonyl-C_1-3-alkyl-oxy, piperazin-1-yl-carbonyl-C_1-3-alkyloxy or 4-(C_1-3-alkyl)-piperazin-1-yl-carbonyl-C_1-3-alkyloxy group,
- a hydroxy-C_1-3-alkyl, C_1-3-alkyloxy-C_1-3-alkyl, amino-C_1-3-alkyl, C_1-3-alkylamino-C_1-3-alkyl, di-(C_1-3-alkyl)-amino-C_1-3-alkyl, pyrrolidin-1-yl-C_1-3-alkyl, piperidin-1-yl-C_1-3-alkyl, morpholin-4-yl-C_1-3-alkyl, piperazin-1-yl-C_1-3-alkyl, 4-(C_1-3-alkyl)-piperazin-1-yl-C_1-3-alkyl group,
- a hydroxy-C_1-3-alkyloxy, C_1-3-alkyloxy-C_1-3-alkyloxy, amino-C_1-3-alkyloxy, C_1-3-alkylamino-C_1-3-alkyloxy, di-(C_1-3-alkyl)-amino-C_1-3-alkyloxy, pyrrolidin-1-yl-C_1-3-alkyloxy, piperidin-1-yl-C_1-3-alkyloxy, morpholin-4-yl-C_1-3-alkyloxy, piperazin-1-yl-C_1-3-alkyloxy, 4-(C_1-3-alkyl)-piperazin-1-yl-C_1-3-alkyloxy group,
- a mercapto, C_1-3-alkylsulphanyl, C_1-3-alkysulphinyl, C_1-3-alkylsulphonyl, C_1-3-alkylsulphonyloxy, trifluoromethylsulphanyl, trifluoromethylsulphinyl or trifluoromethylsulphonyl group,
- a sulpho, aminosulphonyl, C_1-3-alkyl-aminosulphonyl, di-(C_1-3-alkyl)-amino-sulphonyl, pyrrolidin-1-yl-sulphonyl, piperidin-1-yl-sulphonyl, morpholin-4-yl-sulphonyl, piperazin-1-yl-sulphonyl or 4-(C_1-3-alkyl)-piperazin-1-yl-sulphonyl group,
- a methyl or methoxy group substituted by 1 to 3 fluorine atoms,
- an ethyl or ethoxy group substituted by 1 to 5 fluorine atoms,
- a C_2-4-alkenyl or C_2-4-alkynyl group,
- a 2-propen-1-yloxy or 2-propyn-1-yloxy group,
- a C_3-6-cycloalkyl or C_3-6-cycloalkyloxy group,
- a C_3-6-cycloalkyl-C_1-3-alkyl or C_3-6-cycloalkyl-C_1-3-alkyloxy group or
- an aryl, aryloxy, aryl-C_1-3-alkyl or aryl-C_1-3-alkyloxy group,
- R¹¹and R¹², which may be identical or different, in each case denote a hydrogen atom, a fluorine, chlorine, bromine or iodine atom, a C_1-3-alkyl, trifluoromethyl, hydroxy, or C_1-3-alkyloxy group or a cyano group, or
- R¹¹m together with R¹², if they are bound to adjacent carbon atoms, also denote a methylenedioxy, difluoromethylenedioxy, straight-chain C_3-5-alkylene, â€”CHâ• CHâ€”CHâ• CH, â€”CHâ• CHâ€”CHâ• N or â€”CHâ• CHâ€”Nâ• CH group and
- R¹³and R¹⁴, which may be identical or different, in each case denote a hydrogen atom, a fluorine, chlorine or bromine atom, a trifluoromethyl, C_1-3-alkyl or C_1-3-alkyloxy group,

a phenyl group substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-C_2-3-alkenyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-(CH₂)_m-A-(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined and

- A denotes a carbonyl, cyanoiminomethylene, hydroxyiminomethylene or C_1-3-alkyloxyiminomethylene group, m denotes the number 0, 1 or 2 and n denotes the number 1, 2 or 3,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, m and n are as hereinbefore defined and

- B denotes a methylene group which is substituted by a hydroxy, C_1-3-alkyloxy, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, mercapto, C_1-3-alkylsulphanyl,
- C_1-3-alkylsulphinyl or C_1-3-alkylsulphonyl group and is optionally additionally substituted by a methyl or ethyl group,

a heteroaryl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

a C_1-6-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_m-A-(CH₂), group, wherein A, m and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_mâ€”Bâ€”(CH₂), group, wherein B, m and n are as hereinbefore defined,

a R²¹-A-(CH₂)_ngroup wherein R²¹denotes a C_1-3-alkyloxycarbonyl, aminocarbonyl, C_1-3-alkylaminocarbonyl, di-(C_1-3-alkyl)aminocarbonyl, pyrrolidin-1-yl-carbonyl, piperidin-1-yl-carbonyl or morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl, 4-methylpiperazin-1-yl-carbonyl or 4-ethylpiperazin-1-yl-carbonyl group and A and n are as hereinbefore defined,

a C_2-6-alkyl group substituted by a group R_b, wherein

- R_bis isolated from the cyclic nitrogen atom in the 1 position of the xanthine skeleton by at least two carbon atoms and R_bdenotes a hydroxy, C_1-3-alkyloxy, mercapto, C_1-3-alkylsulphanyl, C_1-3-alkylsulphinyl, C_1-3-alkylsulphonyl, amino, C_1-3-alkylamino, di-(C_1-3-alkyl)-amino, pyrrolidin-1-yl, piperidin-1-yl, morpholin-4-yl, piperazin-1-yl or 4-(C_1-3-alkyl)-piperazin-1-yl group,

or a C_3-6-cycloalkyl group,

R²denotes a hydrogen atom,

a C_1-8-alkyl group,

a C_3-6-alkenyl group,

a C_3-6-alkynyl group,

a C_1-6-alkyl group substituted by a group R_a, wherein R_ais as hereinbefore defined,

a C_1-6-alkyl group substituted by a phenyl group, wherein the phenyl ring is substituted by the groups R¹⁰to R¹⁴and R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl group substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-C_2-3-alkenyl group wherein the phenyl moiety is substituted by the groups

R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴are as hereinbefore defined,

a phenyl-(CH₂)_m-A-(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, A, m and n are as hereinbefore defined,

a phenyl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup wherein the phenyl moiety is substituted by R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, B, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_m-A-(CH₂)_ngroup, wherein A, m and n are as hereinbefore defined,

a heteroaryl-(CH₂)_mâ€”Bâ€”(CH₂)_ngroup, wherein B, m and n are as hereinbefore defined,

a C_1-6-alkyl-A-(CH₂), group, wherein A and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_m-A-(CH₂), group, wherein A, m and n are as hereinbefore defined,

a C_3-7-cycloalkyl-(CH₂)_mâ€”Bâ€”(C^1-2), group, wherein B, m and n are as hereinbefore defined,

a R²¹-A-(CH₂), group wherein R²¹, A and n are as hereinbefore defined,

a phenyl-(CH₂)_m-D-C_1-3-alkyl group wherein the phenyl moiety is substituted by the groups R¹⁰to R¹⁴, wherein R¹⁰to R¹⁴, m and D are as hereinbefore defined,

a C_2-6-alkyl group substituted by a group R_b, wherein

- R_bis isolated from the cyclic nitrogen atom in the 3 position of the xanthine skeleton by at least two carbon atoms and is as hereinbefore defined,

or a C_3-6-cycloalkyl group,

R³denotes a C_1-8-alkyl group,

a C_1-4-alkyl group substituted by the group R_c, wherein

- R_cdenotes a C_3-7-cycloalkyl group optionally substituted by one or two C_1-3-alkyl groups,
- a C_5-7-cycloalkenyl group optionally substituted by one or two C_1-3-alkyl groups or an aryl or heteroaryl group,

a C_3-8-alkenyl group,

a C_3-6-alkenyl group substituted by a fluorine, chlorine or bromine atom, or a trifluoromethyl group,

a C_3-8-alkynyl group,

an aryl group or

an aryl-C_2-4-alkenyl group,

and

R⁴denotes an azetidin-1-yl or pyrrolidin-1-yl group which is substituted in the 3 position by a R_eNR_dgroup and may additionally be substituted by one or two C_1-3-alkyl groups, wherein

- R_edenotes a hydrogen atom or a C_1-3-alkyl group and
- R_ddenotes a hydrogen atom, a C_1-3-alkyl group, an R_fâ€”C_1-3-alkyl group or a R_gâ€”C_2-3-alkyl group, wherein
- R_fdenotes a carboxy, C_1-3-alkyloxy-carbonyl, aminocarbonyl, C_1-3-alkylamino-carbonyl, di-(C_1-3-alkyl)-aminocarbonyl, pyrrolidin-1-yl-carbonyl, 2-cyano-pyrrolidin-1-yl-carbonyl, 2-carboxypyrrolidin-1-yl-carbonyl, 2-methoxy-carbonylpyrrolidin-1-yl-carbonyl, 2-ethoxycarbonylpyrrolidin-1-yl-carbonyl, 2-aminocarbonylpyrrolidin-1-yl-carbonyl, 4-cyanothiazolidin-3-yl-carbonyl, 4-carboxythiazolidin-3-yl-carbonyl, 4-methoxycarbonylthiazolidin-3-yl-carbonyl, 4-ethoxycarbonylthiazolidin-3-yl-carbonyl, 4-aminocarbonylthiazolidin-3-yl-carbonyl, piperidin-1-yl-carbonyl, morpholin-4-yl-carbonyl, piperazin-1-yl-carbonyl, 4-methyl-piperazin-1-yl-carbonyl or 4-ethyl-piperazin-1-yl-carbonyl group and
- R_g, which is separated from the nitrogen atom of the R_eNR_dgroup by at least two carbon atoms denotes a hydroxy, methoxy or ethoxy group,

a piperidin-1-yl or hexahydroazepin-1-yl group substituted in the 3 position by an amino, C_1-3-alkylamino or di-(C_1-3-alkyl)-amino group, wherein in each case two hydrogen atoms on the carbon skeleton of the piperidin-1-yl or hexahydroazepin-1-yl group are replaced by a straight-chain alkylene bridge, this bridge containing 2 to 5 carbon atoms if the two hydrogen atoms are located on the same carbon atom, or 1 to 4 carbon atoms, if the hydrogen atoms are located on adjacent carbon atoms, or 1 to 4 carbon atoms, if the hydrogen atoms are located on carbon atoms which are separated by one atom, or 1 to 3 carbon atoms if the two hydrogen atoms are located on carbon atoms separated by two atoms,

a piperazin-1-yl or [1,4]diazepan-1-yl group optionally substituted on the carbon skeleton by one or two C_1-3-alkyl groups,

a 3-imino-piperazin-1-yl, 3-imino-[1,4]diazepan-1-yl or 5-imino-[1,4]diazepan-1-yl group optionally substituted on the carbon skeleton by one or two C_1-3-alkyl groups,