The present invention relates to adenine derivatives, processes for their preparation, pharmaceutical compositions containing them and their use in therapy.

The immune system is comprised of innate and acquired immunity, both of which work cooperatively to protect the host from microbial infections. It has been shown that innate immunity can recognize conserved pathogen-associated molecular patterns through toll-like receptors (TLRs) expressed on the cell surface of immune cells. Recognition of invading pathogens then triggers cytokine production (including interferon alpha(IFNÎ±)) and upregulation of co-stimulatory molecules on phagocytes, leading to modulation of T cell function. Thus, innate immunity is closely linked to acquired immunity and can influence the development and regulation of an acquired response.

TLRs are a family of type I transmembrane receptors characterized by an NH₂-terminal extracellular leucine-rich repeat domain (LRR) and a COOH-terminal intracellular tail containing a conserved region called the Toll/IL-1 receptor (TIR) homology domain. The extracellular domain contains a varying number of LRR, which are thought to be involved in ligand binding. Eleven TLRs have been described to date in humans and mice. They differ from each other in ligand specificities, expression patterns, and in the target genes they can induce.

Ligands which act via TLRs (also known as immune response modifiers (IRMS)) have been developed, for example, the imidazoquinoline derivatives described in U.S. Pat. No. 4,689,338 which include the product Imiquimod for treating genital warts, and the adenine derivatives described in WO 98/01448, WO 99/28321 and WO 2007/034882.

This patent application describes a class of 9-substituted-8-oxoadenine compounds having immuno-modulating properties which act via TLR7 that are useful in the treatment of viral or allergic diseases and cancers.

In accordance with the present invention, there is therefore provided an adenine compound represented by Formula (I):

wherein

- R¹represents hydrogen, hydroxyl, C₁-C₆alkoxy, C₂-C₅alkoxycarbonyl, or a C₆-C₁₀aryl, C₅-C₁₀heteroaryl or C₃-C₈cycloalkyl group, wherein any available carbon atom in each group is optionally substituted by one or more substituents independently selected from halogen, hydroxyl, C₁-C₆alkyl, C₁-C₆haloalkyl, C₁-C₆alkoxy, C₁-C₆haloalkoxy, C₂-C₅alkoxycarbonyl, amino, mono or di-C₁-C₆alkylamino;
- Y¹represents a single bond or C₁-C₆alkylene;
- X¹represents a single bond or an oxygen or sulphur atom, sulphinyl (SO), sulphonyl (SO₂) or NR⁴where R⁴is hydrogen or C_1-6alkyl;
  provided that when R¹is hydroxyl, C_1-6alkoxy or C₂-C₅alkoxycarbonyl and X¹is oxygen, Y₁is other than a single bond;
- L is a bond or a straight or branched C_1-6alkylene group, wherein up to 3 carbon atoms within the alkylene group may be replaced by oxygen, sulfur, SO, SO₂, carbonyl or NR⁵wherein R⁵is hydrogen or C_1-6alkyl; and
- R²is either a saturated or partially unsaturated 4-8 membered heterocycle comprising 1 or 2 hetero atoms selected from nitrogen, oxygen and sulphur, provided that at least one of the heteroatoms is nitrogen, which heterocycle is optionally substituted by one or more groups selected from halogen, hydroxyl, oxo, C_1-6alkoxy, C_2-6alkylcarbonyl, C_1-6alkylsulfonyl, carbamoyl, C_1-6alkylcarbamoyl, di-C_1-6alkylcarbamoyl, C_1-6alkylsulfinyl or an C_1-6alkyl group wherein from 1 to 3 carbon atoms are optionally replaced by oxygen, sulphur, SO, SO₂, carbonyl or a group NR³where R³is hydrogen or C_1-6alkyl;
- or R²is a group of sub formula (i)

- where R⁶is hydrogen or C_1-6alkyl;
- R⁷is hydrogen, or C_1-6alkyl;
- R⁸is hydrogen, C₁-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, a C₆-C₁₀aryl, C₅-C₁₀heteroaryl, C₃-C₈cycloalkyl or a 3-8 membered saturated or partially saturated heterocyclic ring wherein each group may be optionally substituted by one or more groups selected from halogen, cyano, S(O)_mR¹⁰, OR¹⁰, C(O)R¹⁰, CO₂R¹⁰, OC(O)R¹⁰, SO₂NR¹¹R¹², CONR¹¹R¹², NR¹¹R¹², NR¹¹SO₂R¹⁰, NR¹¹CO₂R¹⁰, NR¹¹COR¹⁰, where any C₁-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl or C₃-C₈cycloalkyl groups R⁸may also be optionally substituted by one or more C₆-C₁₀aryl, C₅-C₁₀heteroaryl, a 3-8 membered saturated or partially saturated heterocyclic ring or C₃-C₈cycloalkyl groups and where any C₆-C₁₀aryl or C₅-C₁₀heteroaryl groups R⁸may also be optionally substituted by one or more C₁-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl or C₃-C₈cycloalkyl groups, and where any C₁-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl, C₃-C₈cycloalkyl group, a C₆-C₁₀aryl, C₅-C₁₀heteroaryl or 3-8 membered saturated or partially saturated heterocyclic ring substituents are optionally substituted by one or more groups independently selected from halogen, cyano, S(O)_mR¹³, OR¹³, C(O)R¹³, CO₂R¹³, OC(O)R¹³, SO₂NR¹⁴R¹⁵, CONR¹⁴R¹⁵, NR¹⁴R¹⁵, NR¹³SO₂R¹³, NR¹⁴CO₂R¹³or NR¹⁴COR¹³groups;
- or R⁷and R⁸may be combined together with adjacent carbon atom to form a 3-8 membered saturated carbocycle or a 3-8 membered saturated or partially saturated heterocycle optionally substituted by one or more groups independently selected from halogen, cyano, S(O)_mR¹³, OR¹³, C(O)R¹³, CO₂R¹³, OC(O)R¹³, SO₂NR¹⁴R¹⁵, CONR¹⁴R¹⁵, News, NR¹³SO₂R¹³, NR¹⁴CO₂R¹³or NR¹⁴COR¹³groups;
- R⁹is hydrogen, S(O)_mR¹⁶, C(O)R¹⁶, SO₂NR¹⁷R¹⁸, CONR¹⁷R¹⁸, C₁-C₆alkyl, C₂-C₆alkenyl, C₂-C₆alkynyl or C₃-C₈cycloalkyl group, the latter four groups being optionally substituted by one or more substituents independently selected from halogen, cyano, S(O)_mR¹⁹, OR¹⁹, C(O)R¹⁹, OC(O)R¹⁹, CO₂R¹⁹, SO₂NR²⁰R²¹, CONR²⁰R²¹, NR²⁰R²¹, NR²⁰SO₂R¹⁹, NR²⁰CO₂R¹⁹or NR²⁰COR¹⁹;
- where m is 0, 1 or 2,
  provided that when R⁸is a C₆-C₁₀aryl or a C₈-C₁₀heteroaryl, R⁹is not hydrogen or unsubstituted C₁-C₆alkyl,
  and provided that when R⁷and R⁹are hydrogen or C₁-C₆alkyl, then R⁸is other than C₁-C₆alkyl mono-substituted by C₆-C₁₀aryl or a C₅-C₁₀heteroaryl;
- wherein R¹⁰, R¹³, R¹⁶and R¹⁹are independently selected from hydrogen, C_1-6alkyl, C_2-6alkenyl, C_2-6alkynyl, C₃-C₈cycloalkyl, a C₆-C₁₀aryl or C₅-C₁₀heteroaryl group, which to may be optionally substituted on any available carbon atom by one or more groups selected from halogen, hydroxyl, cyano, C_1-6alkoxy, mercapto, C_1-6alkylthio, C_1-6alkylsulphonyl, carboxy, C_1-6alkylcarbonyloxy, sulphamoyl, C_1-6alkylsulphamoyl, di-C_1-6alkylsulphamoyl, carbamoyl, C_1-6alkylcarbamoyl, di-C_1-6alkylcarbamoyl, amino, C_1-6alkylamino or di-C_1-6alkylamino;
- R¹¹, R¹², R¹⁴, R¹⁵, R¹⁷, R¹⁸, R²⁰or R²¹are independently selected from hydrogen, C_1-6alkyl, C_2-6alkenyl, C_2-6alkynyl, C₃-C₈cycloalkyl, a C₆-C₁₀aryl or C₈-C₁₀heteroaryl group, which may be optionally substituted on any available carbon atom by one or more groups selected from halogen, hydroxyl, cyano, C_1-6alkoxy, mercapto, C_1-6alkylthio, C_1-6alkylsulphonyl, carboxy, C_1-6alkylcarbonyloxy, sulphamoyl, C_1-6alkylsulphamoyl, di-C_1-6alkylsulphamoyl, carbamoyl, C_1-6alkylcarbamoyl, di-C_1-6alkylcarbamoyl, amino, C_1-6alkylamino or di-C_1-6alkylamino;
- or R¹¹and R¹², R¹⁴and R¹⁵, R¹⁷and R¹⁸or R²⁰and R²¹together with the nitrogen atom to which they are attached form a 3- to 8-membered saturated heterocyclic ring comprising a ring nitrogen atom and optionally one or more further heteroatoms independently selected from nitrogen, oxygen, sulphur and sulphonyl, the heterocyclic ring being optionally substituted by one or more substituents independently selected from C_1-6alkyl, C_2-6alkenyl, C_2-6alkynyl, C₃-C₈cycloalkyl, halogen, hydroxyl, cyano, C_1-6alkoxy, C_1-6alkylthio, C_1-6alkylsulphonyl sulphamoyl, C_1-6alkylsulphamoyl, di-C_1-6alkylsulphamoyl, carbamoyl, C_1-6alkylcarbamoyl, di-C_1-6alkylcarbamoyl, amino, C_1-6alkylamino, di-C_1-6alkylamino, amido, or a group NR³⁴CO₂R³⁵or NR³⁴COR³⁵where R³⁴and R³⁵are independently selected from hydrogen and C_1-6alkyl;
  or a pharmaceutically acceptable salt thereof.

In the context of the present specification, unless otherwise stated, an alkyl substituent group or an alkyl moiety in a substituent group may be linear or branched. They may for example contain from 1 to 6 carbon atoms. Examples of C₁-C₆alkyl groups/moieties include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl. Similarly, an alkylene group/moiety may be linear or branched. Examples of C₁-C₆alkylene groups/moieties include methylene, ethylene, n-propylene, n-butylene, n-pentylene, n-hexylene, 1-methylethylene, 2-methylethylene, 1,2-dimethylethylene, 1-ethylethylene, 2-ethylethylene, 1-, 2- or 3-methylpropylene and 1-, 2- or 3-ethylpropylene. An alkenyl or alkynyl group is an unsaturated linear or branched group, containing for example from 2 to 6 carbon atoms.

Cycloalkyl or carbocycle groups are rings containing, for example, from 3 to 8 carbon atoms and are saturated.

Heterocyclic groups are rings which may be saturated, partially unsaturated or unsaturated, and contain from 3 to 20 atoms, at least one and suitably from 1 to 4 atoms are heteroatoms selected from oxygen, sulphur and nitrogen. Rings may be monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s). Monocyclic heterocyclic rings contain from about 3 to 12 ring atoms, with from 1 to 5 heteroatoms selected from N, O, and S, and suitably from 3 to 7 member atoms, in the ring. Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring. Bicyclic heterocycles contain from about 7 to about 17 ring atoms, suitably from 7 to 12 ring atoms. Bicyclic heterocyclic(s) rings may be fused, spiro, or bridged ring systems.

For the avoidance of doubt, rings which are described as being â€œpartially unsaturatedâ€ may contain one or more multiple bonds but they are not aromatic in nature.

Examples of heterocyclic groups which are saturated or partially saturated include cyclic ethers (oxiranes) such as ethyleneoxide, tetrahydrofuran, dioxane, and substituted cyclic ethers. Heterocycles containing nitrogen include, for example, azetidine, pyrrolidine, piperidine, piperazine, tetrahydrotriazine, tetrahydropyrazole, and the like. Typical sulfur containing heterocycles include tetrahydrothiophene, dihydro-1,3-dithiol-2-yl, and hexahydrothiepin-4-yl. Other heterocycles include dihydro-oxathiol-4-yl, tetrahydro-oxazolyl, tetrahydro-oxadiazolyl, tetrahydrodioxazolyl, tetrahydro-oxathiazolyl, hexahydrotriazinyl, tetrahydro-oxazinyl, morpholinyl, thiomorpholinyl, tetrahydropyrimidinyl, dioxolinyl, octahydrobenzofuranyl, octahydrobenzimidazolyl, and octahydrobenzothiazolyl. For heterocycles containing sulfur, the oxidized sulfur heterocycles containing SO or SO₂groups are also included. Examples include the sulfoxide and sulfone forms of tetrahydrothiophene. A suitable value for a heterocyclyl group which bears 1 or 2 oxo or thioxo substituents is, for example, 2-oxopyrrolidinyl, to 2-thioxopyrrolidinyl, 2-oxoimidazolidinyl, 2-thioxoimidazolidinyl, 2-oxopiperidinyl, 2,5-dioxopyrrolidinyl, 2,5-dioxoimidazolidinyl or 2,6-dioxopiperidinyl.

Heterocyclic groups which are aromatic in nature are referred to as â€œheteroarylâ€ groups. These groups are aromatic mono-, bi-, or polycyclic heterocyclic ring incorporating one or is more (for example 1-4) heteroatoms selected from N, O, and S. The term heteroaryl includes both monovalent species and divalent species. Examples of heteroaryl groups include furyl, pyrrolyl, thienyl, oxazolyl, isoxazolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, 1,3,5-triazenyl, benzofuranyl, indolyl, isoindolyl, benzothienyl, benzoxazolyl, benzimidazolyl, benzothiazolyl, benzothiazolyl, indazolyl, purinyl, benzofurazanyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, cinnolinyl, pteridinyl, naphthyridinyl, carbazolyl, phenazinyl, benzisoquinolinyl, pyridopyrazinyl, thieno[2,3-b]furanyl, 2H-furo[3,2-b]-pyranyl, 5H-pyrido[2,3-d]-o-oxazinyl, 1H-pyrazolo[4,3-d]-oxazolyl, 4H-imidazo[4,5-d]thiazolyl, pyrazino[2,3-d]pyridazinyl, imidazo[2,1-b]thiazolyl, imidazo[1,2-b][1,2,4]triazinyl. â€œHeteroarylâ€ also covers ring systems wherein at least one ring is an aromatic ring containing 1 or more heteroatoms selected from O, S and N and one or more of the other rings is a non-aromatic, saturated or partially unsaturated ring optionally containing one or more heteroatoms selected from O, S and N, for example 1,2,3,4-tetrahydro-1,8-naphthyridinyl, 1,2,3,4-tetrahydropyrido[2,3-b]pyrazinyl and 3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazinyl.

Preferably R¹represents hydrogen.

In a particular embodiment, Y¹represents unsubstituted C_1-6alkylene such as a linear C_1-6alkylene for instance methyl, ethyl, propyl, n-butyl, n-pentyl or n-hexyl. In particular, R¹is n-butyl

Particular examples of X¹groups are oxygen, sulphur, or NR⁴, where R⁴is as defined above. When X¹is a NR⁴group, suitable R⁴groups include hydrogen or methyl, and in particular hydrogen.

In a further embodiment, X¹represents oxygen.

Where any of the carbon atoms within the L group are replaced by oxygen, sulfur, SO, SO₂, carbonyl or NR⁵, these are suitably arranged at an intermediate position in the alkylene chain so that the terminal atoms of L are carbon.

Where L contains an NR⁵group, R⁵is suitably hydrogen or C_1-6alkyl such as hydrogen or methyl. In a particular embodiment, up to 2 carbon atoms within the alkylene group of L may be replaced by oxygen, sulfur, SO, SO₂, carbonyl or NR⁵. In a further particular embodiment, no more than one carbon atom within L is replaced by oxygen, sulfur, SO, SO₂, carbonyl or NR⁵.

In a particular embodiment, L is a bond or a straight or branched C_1-6alkylene, and in particular a straight chain alkylene such as n-propylene.

In another embodiment, L is an alkylene chain wherein two carbon atoms are replaced, one by a carbonyl group and one by a group NR⁵.

In a further embodiment, R²is a saturated or partially unsaturated 4-8 membered heterocycle comprising 1 or 2 heteroatoms selected from nitrogen, oxygen and sulphur, provided that at least one of the heteroatoms is nitrogen, which may be optionally substituted as described above. In particular, R²is pyrrolidine, piperidine, piperidine, morpholine, thiomorpholine, thiomorpholine-1-oxide or thiomorpholine-1,1-dioxide.

Suitably R²is a saturated nitrogen containing heterocycle such as pyrrolidinyl or morpholine.

In a particular embodiment, the ring R²is linked to the group L by way of a ring nitrogen atom.

The ring R²may be unsubstituted.

Alternatively the ring R²may carry one or more substituents, for example from one to three substituents independently selected from halogen, hydroxyl, oxo, C_1-6alkoxy, C_2-6-alkylcarbonyl, C_1-6alkylsulfonyl, carbamoyl, C_1-6alkylcarbamoyl, di-C_1-6alkylcarbamoyl, C_1-6alkylsulfinyl or a C_1-6alkyl group wherein from 1 to 3 carbon atoms are optionally replaced by oxygen, sulphur, SO, SO₂, carbonyl or a group NR³where R³is hydrogen or

In particular, when R²is a ring, it is optionally substituted by one or two oxo groups.

A further example of a suitable substituent for R²is an alkyl group which is optionally interposed with an oxygen atom, so as to form a alkoxyalkyl group such as a C_1-3alkoxyC_1-2alkyl group, for instance methoxymethyl.

Another suitable substitutent for a ring R²is di-C_1-6alkylcarbamoyl, such as dimethylcarbamoyl.

In another embodiment R²is a group of sub formula (i)

where R⁶, R⁷, R⁸and R⁹are as defined above.

In particular, R⁶and R⁷are independently hydrogen or C_1-3alkyl.

For instance, R⁶is hydrogen or methyl.

In a further embodiment, R⁷is hydrogen or methyl

Suitably, R⁸is hydrogen or C_1-6alkyl which may be optionally substituted as defined above, such as optionally substituted methyl.

In a particular embodiment, R⁸is hydrogen or a C_1-6alkyl optionally substituted by one or more groups selected from C_2-5alkoxycarbonyl, carboxy, hydroxy, amino optionally substituted by one or two C_1-6alkyl groups which may be the same or different, carbamoyl optionally substituted by one or two C_1-6alkyl groups which may be the same or different 6-10 membered aryl optionally substituted by halogen, hydroxy, C_1-6alkyl, C_1-6alkoxy, C_1-6haloalkyl, C_1-6haloalkoxy, or amino optionally substituted by one or two C_1-6alkyl groups which may be the same or different.

For example R⁸is a C_1-6alkyl group substituted by C_1-6alkoxy such as methoxy.

Particular examples of R⁹include hydrogen or a CONR¹⁷R¹⁸where R¹⁷and R¹⁸are as defined above. In particular, R¹⁷and R¹⁸are C_1-6alkyl groups such as methyl, or R¹⁷and R¹⁸together with the nitrogen atom to which they are attached form a a 3- to 8-membered saturated heterocyclic ring comprising a ring nitrogen atom and optionally one or more further heteroatoms independently selected from nitrogen, oxygen, sulphur and sulphonyl, such as a morpholine ring.

Examples of compounds of the invention include:

6-Amino-2-butoxy-9-(3-pyrrolidin-1-ylpropyl)-7,9-dihydro-8H-purin-8-one;
1-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]-N,N-dimethyl-L-prolinamide;
6-Amino-2-butoxy-9-{3-[(2S)-2-(methoxymethyl)pyrrolidin-1-yl]propyl}-7,9-dihydro-8H-purin-8-one;
N²-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]-N¹,N¹,N²-trimethylglycinamide;
1-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]pyrrolidine-2,5-dione;
6-Amino-2-butoxy-9-(3-{[(1S)-2-methoxy-1-methylethyl]amino}propyl)-7,9-dihydro-8H-purin-8-one; and
6-Amino-2-butoxy-9-{3-[methyl-(2-morpholin-4-yl-2-oxo-ethyl)-amino]-propyl}-7,9-dihydro-purin-8-one,
and pharmaceutically acceptable salts thereof.

The present invention further provides a process for the preparation of a compound of formula (I) or a pharmaceutically acceptable salt thereof as defined above which comprises reacting a compound of formula (II)

wherein X¹, Y¹and L are as defined in formula (I), and Z is a leaving group, with a compound of formula (III)

Hâ€”R²â€ƒâ€ƒ(III)

where R²is as defined in relation to formula (I), except that where R²is a substituted or unsubstituted saturated or unsaturated 4-8 membered heterocycle, it is linked to the H group of formula (III) by way of a nitrogen atom.

Suitable leaving groups Z are halogen atoms such as bromine, or chlorine, as well as mesylate and tosylate. The reaction is suitably carried out in an organic solvent such as dimethylsulphoxide (DMSO), acetonitrile or N,N-dimethylformamide for example, using an excess of the amine, preferably at moderate to elevated temperature, e.g. at a temperature in the range from 0 to 150Â° C. The reaction may be conducted in the presence of a base such as an alkali metal carbonate (e.g. sodium carbonate or potassium carbonate).

Compounds of formula (II) may be prepared as illustrated in the following reaction scheme:

The compound of formula (B) is prepared by reacting the compound of formula (A) with ammonia in an organic solvent such as methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, diglyme, acetonitrile or an aqueous mixture of any one of the preceding solvents. The reaction may be carried out in an autoclave, and at a temperature, for example, in the range from 20 to 200Â° C.

Compounds of formula (C) may be prepared by reacting the compound of formula (B) with an alkanol in the presence of a base such as sodium hydride or potassium t-butoxide and in an organic solvent such as tetrahydrofuran, 1,4-dioxane, diglyme, N,N-dimethylformamide or dimethylsulfoxide, preferably at elevated temperature, e.g. at a temperature in the range from 20 to 150Â° C. Alternatively an alkali metal such as sodium may be dissolved in the alkanol and then reacted with the compound of formula (B), preferably at elevated temperature, e.g. at a temperature in the range from 20 to 150Â° C.

Compounds of formula (D) are prepared by brominating a compound of formula (C). The to reaction may be carried out using a brominating agent such as bromine, hydroperbromic acid or N-bromosuccinimide (NBS), in an organic solvent such as carbon tetrachloride, methylene chloride, dichloroethane, diethyl ether, acetic acid or carbon disulfide. The reaction temperature will generally be in the range from 0Â° C. to the boiling point of the solvent.

Compounds of formula (E) are prepared by reacting a compound of formula (D) with sodium methoxide in an organic solvent such as methanol and at a temperature, for example, in the range from 20 to 150Â° C.

Compounds of formula (F) may be obtained by treating a compound of formula (E) with an acid such as trifluoroacetic acid in an organic solvent such as methanol.

Compounds of formula (G) are prepared by reacting a compound of formula (F) with a compound of formula Z-L-Z wherein L is as defined in relation to formula (I) and each Z is a leaving group such as a halogen, mesylate or triflate. The reaction may be carried out in an organic solvent such as N,N-dimethylformamide, dimethylsulfoxide or acetonitrile with a base present, preferably at room temperature (20Â° C.). A base such as an alkali metal carbonate, e.g. sodium carbonate or potassium carbonate; an alkaline earth metal carbonate, e.g. calcium carbonate; a metal hydroxide, e.g. sodium hydroxide or potassium hydroxide; a metal hydrogenate, e.g. sodium hydride; or a metal alkoxide, e.g. potassium t-butoxide, may be used.

Compounds of formula (II) may be obtained by treatment of a compound of formula (G) with an acid. The reaction may be carried out in an organic solvent such as methanol using either an inorganic acid such as hydrochloric acid, hydrobromic acid or sulfuric acid, or an organic acid such as trifluoroacetic acid.

Alternatively, compounds of formula (I) may be prepared by reacting a compound of formula (IV)

where L, R², R¹, X¹and Y¹are as defined in relation to formula (I) and R³⁸is a C_1-4alkyl group such as methyl, with an acid which is either an inorganic acid such as hydrochloric acid, hydrobromic acid or sulfuric acid, or an organic acid such as trifluoroacetic acid. The reaction may be carried out in an organic solvent such as methanol.

Compounds of formula (IV) may be prepared by reacting a compound of formula (IVA)

wherein L, R², R¹, X¹and Y¹are as defined in relation to formula (I), and R³⁸is as defined in relation to formula (IV), with a compound of formula (V)

Z-L-R²â€ƒâ€ƒ(V)

wherein L and R²are as defined in relation to formula (I) and Z is a leaving group such as a halogen, mesylate or triflate. Reaction conditions are similar to those described above for the reaction of the compound of formula G to form the compound of formula II above.

Compounds of formula (IVA) are analogous to compound G above and can be prepared using analogous methods.

In an alternative embodiment, compounds of formula (I) may be prepared by reacting a compound of formula (VI)

where R²and L are as defined in relation to formula (I) and Z¹is a leaving group such as halogen, in particular chlorine, with a compound of formula (VII)

R¹â€”Y¹â€”X¹â€”Hâ€ƒâ€ƒ(VII)

where R¹, Y₁and X¹are as defined in relation to formula (I). The reaction is suitably carried out in the presence of a base, such as an alkali or alkaline earth metal carbonate or hydride, such as sodium or potassium carbonate or hydride or an organic base such as triethylamine, in particular where X¹is an oxygen or sulphur atom. It may be effected in the presence of an organic solvent such as an alcohol such as propenol or butanol, tetrahydrofuran, dimethylformamide, dimethylsulphoxide or diglyme, at elevated temperatures for example in the range of from 50-200Â° C.

Compounds of formula (VI) are suitably prepared by reacting a compound of formula (VIII)

where L and R²are as defined in relation to formula (I) and Zâ€² is as defined in relation to formula (VI) with a metal alkoxide such as sodium methoxide, following by treatment with an acid. The reaction is suitably effected in an organic solvent such as diethylether, tetrahydrofuran or 1,4-dioxane at a temperature in the range of from 0Â° C. to the boiling point of the solvent.

Compounds of formula (VIII) can, in their turn be prepared by bromination of a compound of formula (IX)

where L and R²are as defined in relation to formula (I) and Zâ€² is as defined in relation to formula (VI) using conditions analogous to those described above in relation to the preparation of compound (D).

Compounds of formula (IX) can be prepared by coupling compounds of formula (X)

where Z¹is as defined above, with a compound of formula (V) as defined above, using conditions broadly analogous to those described in relation to the reaction of compound (IV) and (V).

Compounds of formula (I) may also be prepared by reacting a compound of formula (XI)

where R¹, X¹, Y¹, L and R²are as defined above in relation to formula (I) using conditions similar to those described above for the conversion of a compound of formula (VIII) to a compound of formula (VI).

Compounds of formula (XI) may be prepared using for example a method outlined in the following scheme:

Couplings of compounds (V) and (VII) can be carried out using conditions similar to those described above in relation to the reactions in which these reagents take part.

In a further embodiment, compounds of formula (I) may be prepared by the following general scheme:

where R¹, X¹, Y¹, L and R²are as defined in relation to formula (I) and Z²is a leaving group, such as halogen for example chlorine.

In this scheme, compounds of formula (I) may be prepared by reacting a compound of formula (XIV) with a compound of formula (XV) in the presence of a base such as an alkali or alkaline earth metal carbonate, hydroxide or hydride such as sodium or potassium carbonate, hydroxide or hydride. The reaction is suitably effected in an organic solvent to such as a halogenated hydrocarbon, for example carbon tetrachloride, chloroform etc. at a temperature in the range of from 0Â° C. to the boiling point of the solvent.

Compounds of formula (XIV) are suitably prepared by reacting a compound of formula (XVII) with an appropriate cyclising agent. For example, where X¹is amino, the cyclising is agent will be guanidine, where X¹is hydroxyl, the cyclising agent is urea and where X¹is mercapto, the cyclising agent is benzoyliothiocyanate. The reaction can be effected in the presence of a base such as those described above and an organic solvent such as THF etc. at temperatures conveniently in the range of from room temperature to about the boiling point of the solvent.

Alternatively, compounds of formula (XVII) can be cyclised directly to compounds of formula (I) by reaction with a compound of formula (XVI). Again the reaction may be effected in the presence of a base such as alkali or alkaline earth metal carbonate, hydroxide or hydride such as sodium or potassium carbonate, hydroxide or hydride or an organic base such as triethylamine, diisopropylamine, pyridine or a metal alkoxide such as sodium methoxide. Organic solvents may be employed such as tetrahydrofuan or an alkyl alcohol such as methanol or ethanol. Temperatures in the range of from room temperature to the boiling point of the solvent may be used.

Compounds of formula (XVII) may be prepared by reacting a compound of formula (XVIII) with a compound of formula (XIX). Again the reaction is suitably effected in the presence of a base such as alkali or alkaline earth metal carbonate, hydroxide or hydride such as sodium or potassium carbonate, hydroxide or hydride or an organic base such as triethylamine, diisopropylamine, pyridine or a metal alkoxide such as sodium methoxide. Organic solvents may be employed such as tetrahydrofuan or an alkyl alcohol such as methanol or ethanol. Temperatures in the range of from 0Â° C. to the boiling point of the solvent may be used.

Compounds of formula (V), (VII), (X) (XV), (XVI) (XVIII), (XIX) as well as compounds of formula Z-L-Z described above are known compounds or they can be prepared from known compounds by conventional methods, for example as described in WO2005092893.

It will be appreciated by those skilled in the art that in the processes of the present invention certain functional groups such as hydroxyl or amino groups in the reagents may need to be protected by protecting groups. Thus, the preparation of the compounds of formula (I) may involve, at an appropriate stage, the removal of one or more protecting groups.

The protection and deprotection of functional groups is described in â€˜Protective Groups in Organic Chemistryâ€™, edited by J. W. F. McOmie, Plenum Press (1973) and â€˜Protective Groups in Organic Synthesisâ€™, 3^rdedition, T. W. Greene and P. G. M. Wuts, Wiley-Interscience (1999).

The compounds of formula (I) above may be converted to a pharmaceutically acceptable salt thereof, preferably an acid addition salt such as a hydrochloride, hydrobromide, trifluoroacetate, sulphate, phosphate, acetate, fumarate, maleate, tartrate, lactate, citrate, pyruvate, succinate, oxalate, methanesulphonate or p-toluenesulphonate.

Compounds of formula (I) are capable of existing in stereoisomeric forms. It will be understood that the invention encompasses the use of all geometric and optical isomers (including atropisomers) of the compounds of formula (I) and mixtures thereof including racemates. The use of tautomers and mixtures thereof also form an aspect of the present invention. Enantiomerically pure forms are particularly desired.

The compounds of formula (I) and their pharmaceutically acceptable salts have activity as pharmaceuticals, in particular as modulators of toll-like receptor (especially TLR⁷) activity, and thus may be used in the treatment of:

1. respiratory tract: obstructive diseases of the airways including: asthma, including bronchial, allergic, intrinsic, extrinsic, exercise-induced, drug-induced (including aspirin and NSAID-induced) and dust-induced asthma, both intermittent and persistent and of all severities, and other causes of airway hyper-responsiveness; chronic obstructive pulmonary disease (COPD); bronchitis, including infectious and eosinophilic bronchitis; emphysema; bronchiectasis; cystic fibrosis; sarcoidosis; farmer's lung and related diseases; hypersensitivity pneumonitis; lung fibrosis, including cryptogenic fibrosing alveolitis, idiopathic interstitial pneumonias, fibrosis complicating anti-neoplastic therapy and chronic infection, including tuberculosis and aspergillosis and other fungal infections; complications of lung transplantation; vasculitic and thrombotic disorders of the lung vasculature, and pulmonary hypertension; antitussive activity including treatment of chronic cough associated with inflammatory and secretory conditions of the airways, and iatrogenic cough; acute and chronic rhinitis including rhinitis medicamentosa, and vasomotor rhinitis; perennial and seasonal allergic rhinitis including rhinitis nervosa (hay fever); nasal polyposis; acute viral infection including the common cold, and infection due to respiratory syncytial virus, influenza, coronavirus (including SARS) and adenovirus;
2. skin: psoriasis, atopic dermatitis, contact dermatitis or other eczematous dermatoses, and delayed-type hypersensitivity reactions; phyto- and photodermatitis; seborrhoeic dermatitis, dermatitis herpetiformis, lichen planus, lichen sclerosus et atrophica, pyoderma gangrenosum, skin sarcoid, discoid lupus erythematosus, pemphigus, pemphigoid, epidermolysis bullosa, urticaria, angioedema, vasculitides, toxic erythemas, cutaneous eosinophilias, alopecia greata, male-pattern baldness, Sweet's syndrome, Weber-Christian syndrome, erythema multiforme; cellulitis, both infective and non-infective; panniculitis; cutaneous lymphomas, non-melanoma skin cancer and other dysplastic lesions; drug-induced disorders including fixed drug eruptions;
3. eyes: blepharitis; conjunctivitis, including perennial and vernal allergic conjunctivitis; iritis; anterior and posterior uveitis; choroiditis; autoimmune, degenerative or inflammatory disorders affecting the retina; ophthalmitis including sympathetic ophthalmitis; sarcoidosis; infections including viral, fungal, and bacterial;
4. genitourinary: nephritis including interstitial and glomerulonephritis; nephrotic syndrome; cystitis including acute and chronic (interstitial) cystitis and Hunner's ulcer; acute and chronic urethritis, prostatitis, epididymitis, oophoritis and salpingitis; vulvo-vaginitis; Peyronie's disease; erectile dysfunction (both male and female);
5. allograft rejection: acute and chronic following, for example, transplantation of kidney, heart, liver, lung, bone marrow, skin or cornea or following blood transfusion; or chronic graft versus host disease;
6. other auto-immune and allergic disorders including rheumatoid arthritis, irritable bowel syndrome, systemic lupus erythematosus, multiple sclerosis, Hashimoto's thyroiditis, Graves' disease, Addison's disease, diabetes mellitus, idiopathic thrombocytopaenic purpura, eosinophilic fasciitis, hyper-IgE syndrome, antiphospholipid syndrome and Sazary syndrome;
7. oncology: treatment of common cancers including prostate, breast, lung, ovarian, pancreatic, bowel and colon, stomach, skin and brain tumors and malignancies affecting the bone marrow (including the leukaemias) and lymphoproliferative systems, such as Hodgkin's and non-Hodgkin's lymphoma; including the prevention and treatment of metastatic disease and tumour recurrences, and paraneoplastic syndromes; and,
8. infectious diseases: virus diseases such as genital warts, common warts, plantar warts, hepatitis B, hepatitis C, herpes simplex virus, molluscum contagiosum, variola, human immunodeficiency virus (HIV), human papilloma virus (HPV), cytomegalovirus (CMV), varicella zoster virus (VZV), rhinovirus, adenovirus, coronavirus, influenza, para-influenza; bacterial diseases such as tuberculosis and mycobacterium avium, leprosy; other infectious diseases, such as fungal diseases, chlamydia, candida, aspergillus, cryptococcal meningitis, pneumocystis carnii, cryptosporidiosis, histoplasmosis, toxoplasmosis, trypanosome infection and leishmaniasis.

Thus, the present invention provides a compound of formula (I) or a pharmaceutically-acceptable salt thereof as hereinbefore defined for use in therapy.

In a further aspect, the present invention provides the use of a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined in the manufacture of a medicament for use in therapy.

In the context of the present specification, the term â€œtherapyâ€ also includes â€œprophylaxisâ€ unless there are specific indications to the contrary. The terms â€œtherapeuticâ€ and â€œtherapeuticallyâ€ should be construed accordingly.

Prophylaxis is expected to be particularly relevant to the treatment of persons who have suffered a previous episode of, or are otherwise considered to be at increased risk of, the disease or condition in question. Persons at risk of developing a particular disease or condition generally include those having a family history of the disease or condition, or those who have been identified by genetic testing or screening to be particularly susceptible to developing the disease or condition.

In particular, the compounds of the invention may be used in the treatment of asthma, COPD, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, cancer, hepatitis B, hepatitis C, HIV, HPV, bacterial infections and dermatosis.

The anti-cancer treatment defined hereinbefore may be applied as a sole therapy or may involve, in addition to the compound of the invention, conventional surgery or radiotherapy or chemotherapy. Such chemotherapy may include one or more of the following categories of anti-tumour agents:â€”

(i) other antiproliferative/antineoplastic drugs and combinations thereof, as used in medical oncology, such as alkylating agents (for example cis-platin, oxaliplatin, carboplatin, cyclophosphamide, nitrogen mustard, melphalan, chlorambucil, busulphan, temozolamide and nitrosoureas); antimetabolites (for example gemcitabine and antifolates such as fluoropyrimidines like 5-fluorouracil and tegafur, raltitrexed, methotrexate, cytosine arabinoside, and hydroxyurea); antitumour antibiotics (for example anthracyclines like adriamycin, bleomycin, doxorubicin, daunomycin, epirubicin, idarubicin, mitomycin-C, dactinomycin and mithramycin); antimitotic agents (for example vinca alkaloids like vincristine, vinblastine, vindesine and vinorelbine and taxoids like taxol and taxotere and polokinase inhibitors); and topoisomerase inhibitors (for example epipodophyllotoxins like etoposide and teniposide, amsacrine, topotecan and camptothecin);
(ii) cytostatic agents such as antioestrogens (for example tamoxifen, fulvestrant, toremifene, raloxifene, droloxifene and iodoxyfene), antiandrogens (for example bicalutamide, flutamide, nilutamide and cyproterone acetate), LHRH antagonists or LHRH agonists (for example goserelin, leuprorelin and buserelin), progestogens (for example megestrol acetate), aromatase inhibitors (for example as anastrozole, letrozole, vorazole and exemestane) and inhibitors of
5Î±-reductase such as finasteride;
(iii) anti-invasion agents (for example c-Src kinase family inhibitors like 4-(6-chloro-2,3-methylenedioxyanilino)-7-[2-(4-methylpiperazin-1-yl)ethoxy]-5-tetrahydropyran-4-yloxyquinazoline (AZD0530; International Patent Application WO 01/94341) and N-(2-chloro-6-methylphenyl)-2-{6-[4-(2-hydroxyethyl)piperazin-1-yl]-2-methylpyrimidin-4-ylamino}thiazole-5-carboxamide (dasatinib, BMS-354825; J. Med. Chem., 2004, 47, 6658-6661), and metalloproteinase inhibitors like marimastat, inhibitors of urokinase plasminogen activator receptor function or antibodies to Heparanase);
(iv) inhibitors of growth factor function: for example such inhibitors include growth factor antibodies and growth factor receptor antibodies (for example the anti-erbB2 antibody trastuzumab [Herceptinâ„¢], the anti-EGFR antibody panitumumab, the anti-erbB1 antibody cetuximab [Erbitux, C225] and any growth factor or growth factor receptor antibodies disclosed by Stern et al. Critical reviews in oncology/haematology, 2005, Vol. 54, pp 11-29); such inhibitors also include tyrosine kinase inhibitors, for example inhibitors of the epidermal growth factor family (for example EGFR family tyrosine kinase inhibitors such as
N-(3-chloro-4-fluorophenyl)-7-methoxy-6-(3-morpholinopropoxy)quinazolin-4-amine (gefitinib, ZD 1839), N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine (erlotinib, OSI-774) and 6-acrylamido-N-(3-chloro-4-fluorophenyl)-7-(3-morpholinopropoxy)-quinazolin-4-amine (CI 1033), erbB2 tyrosine kinase inhibitors such is as lapatinib, inhibitors of the hepatocyte growth factor family, inhibitors of the platelet-derived growth factor family such as imatinib, inhibitors of serine/threonine kinases (for example Ras/Raf signalling inhibitors such as farnesyl transferase inhibitors, for example sorafenib (BAY 43-9006)), inhibitors of cell signalling through MEK and/or AKT kinases, inhibitors of the hepatocyte growth factor family, c-kit inhibitors, abl kinase inhibitors, IGF receptor (insulin-like growth factor) kinase inhibitors; aurora kinase inhibitors (for example AZD1152, PH739358, VX-680, MLN8054, R763, MP235, MP529, VX-528 AND AX39459) and cyclin dependent kinase inhibitors such as CDK2 and/or CDK4 inhibitors;
(v) antiangiogenic agents such as those which inhibit the effects of vascular endothelial growth factor, [for example the anti-vascular endothelial cell growth factor antibody bevacizumab (Avastinâ„¢) and VEGF receptor tyrosine kinase inhibitors such as 4-(4-bromo-2-fluoroanilino)-6-methoxy-7-(1-methylpiperidin-4-ylmethoxy)quinazoline (ZD6474; Example 2 within WO 01/32651), 4-(4-fluoro-2-methylindol-5-yloxy)-6-methoxy-7-(3-pyrrolidin-1-ylpropoxy)quinazoline (AZD2171; Example 240 within WO 00/47212), vatalanib (PTK787; WO 98/35985) and SUI 1248 (sunitinib; WO 01/60814), compounds such as those disclosed in International Patent Applications WO97/22596, WO 97/30035, WO 97/32856 and WO 98/13354 and compounds that work by other mechanisms (for example linomide, inhibitors of integrin Î±vÎ²3 function and angiostatin)];
(vi) vascular damaging agents such as Combretastatin A4 and compounds disclosed in International Patent Applications WO 99/02166, WO 00/40529, WO 00/41669, WO 01/92224, WO 02/04434 and WO 02/08213;
(vii) antisense therapies, for example those which are directed to the targets listed above, such as ISIS 2503, an anti-ras antisense;
(viii) gene therapy approaches, including for example approaches to replace aberrant genes such as aberrant p53 or aberrant BRCA1 or BRCA2, GDEPT (gene-directed enzyme pro-drug therapy) approaches such as those using cytosine deaminase, thymidine kinase or a bacterial nitroreductase enzyme and approaches to increase patient tolerance to chemotherapy or radiotherapy such as multi-drug resistance gene therapy; and
(ix) immunotherapy approaches, including for example ex-vivo and in-vivo approaches to increase the immunogenicity of patient tumour cells, such as transfection with cytokines such as interleukin 2, interleukin 4 or granulocyte-macrophage colony stimulating factor, approaches to decrease T-cell anergy, approaches using transfected immune cells such as cytokine-transfected dendritic cells, approaches using cytokine-transfected tumour cell lines and approaches using anti-idiotypic antibodies.

The invention still further provides a method of treating, or reducing the risk of, an obstructive airways disease or condition (e.g. asthma or COPD) which comprises administering to a patient in need thereof a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined.

For the above-mentioned therapeutic uses the dosage administered will, of course, vary with the compound employed, the mode of administration, the treatment desired and the disorder indicated. For example, the daily dosage of the compound of the invention, if inhaled, may be in the range from 0.05 micrograms per kilogram body weight (Î¼g/kg) to 100 micrograms per kilogram body weight (Î¼g/kg). Alternatively, if the compound is administered orally, then the daily dosage of the compound of the invention may be in the range from 0.01 micrograms per kilogram body weight (Î¼g/kg) to 100 milligrams per kilogram body weight (mg/kg).

The compounds of formula (I) and pharmaceutically acceptable salts thereof may be used on their own but will generally be administered in the form of a pharmaceutical composition in which the formula (I) compound/salt (active ingredient) is in association with a pharmaceutically acceptable adjuvant, diluent or carrier. Conventional procedures for the selection and preparation of suitable pharmaceutical formulations are described in, for example, â€œPharmaceuticalsâ€”The Science of Dosage Form Designsâ€ , M. E. Aulton, Churchill Livingstone, 1988.

Depending on the mode of administration, the pharmaceutical composition will preferably comprise from 0.05 to 99% w (percent by weight), more preferably from 0.05 to 80% w, still more preferably from 0.10 to 70% w, and even more preferably from 0.10 to 50% w, of active ingredient, all percentages by weight being based on total composition.

The present invention also provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined, in association with a pharmaceutically acceptable adjuvant, diluent or carrier.

The invention further provides a process for the preparation of a pharmaceutical composition of the invention which comprises mixing a compound of formula (I) or a pharmaceutically acceptable salt thereof as hereinbefore defined with a pharmaceutically acceptable adjuvant, diluent or carrier.

The pharmaceutical compositions may be administered topically (e.g. to the skin or to the lung and/or airways) in the form, e.g., of creams, solutions, suspensions, heptafluoroalkane (HFA) aerosols and dry powder formulations, for example, formulations in the inhaler device known as the TurbuhalerÂ®; or systemically, e.g. by oral administration in the form of tablets, capsules, syrups, powders or granules; or by parenteral administration in the form of a sterile solution, suspension or emulsion for injection (including intravenous, subcutaneous, intramuscular, intravascular or infusion); or by rectal administration in the form of suppositories.

Dry powder formulations and pressurized HFA aerosols of the compounds of the invention (including pharmaceutically acceptable salts) may be administered by oral or nasal inhalation. For inhalation, the compound is desirably finely divided. The finely divided compound preferably has a mass median diameter of less than 10 micrometres (Î¼m), and may be suspended in a propellant mixture with the assistance of a dispersant, such as a C₈-C₂₀fatty acid or salt thereof, (for example, oleic acid), a bile salt, a phospholipid, an alkyl saccharide, a perfluorinated or polyethoxylated surfactant, or other pharmaceutically acceptable dispersant.

The compounds of the invention may also be administered by means of a dry powder inhaler. The inhaler may be a single or a multi dose inhaler, and may be a breath actuated dry powder inhaler.

One possibility is to mix the finely divided compound of the invention with a carrier substance, for example, a mono-, di- or polysaccharide, a sugar alcohol, or another polyol. Suitable carriers are sugars, for example, lactose, glucose, raffinose, melezitose, lactitol, maltitol, trehalose, sucrose, mannitol; and starch. Alternatively the finely divided compound may be coated by another substance. The powder mixture may also be dispensed into hard gelatine capsules, each containing the desired dose of the active compound.

Another possibility is to process the finely divided powder into spheres which break up during the inhalation procedure. This spheronized powder may be filled into the drug reservoir of a multidose inhaler, for example, that known as the TurbuhalerÂ® in which a dosing unit meters the desired dose which is then inhaled by the patient. With this system the active ingredient, with or without a carrier substance, is delivered to the patient.

For oral administration the compound of the invention may be admixed with an adjuvant or a carrier, for example, lactose, saccharose, sorbitol, mannitol; a starch, for example, potato starch, corn starch or amylopectin; a cellulose derivative; a binder, for example, gelatine or polyvinylpyrrolidone; and/or a lubricant, for example, magnesium stearate, calcium stearate, polyethylene glycol, a wax, paraffin, and the like, and then compressed into tablets. If coated tablets are required, the cores, prepared as described above, may be coated with a concentrated sugar solution which may contain, for example, gum arabic, gelatine, talcum and titanium dioxide. Alternatively, the tablet may be coated with a suitable polymer dissolved in a readily volatile organic solvent.

For the preparation of soft gelatine capsules, the compound of the invention may be admixed with, for example, a vegetable oil or polyethylene glycol. Hard gelatine capsules may contain granules of the compound using either the above-mentioned excipients for tablets. Also liquid or semisolid formulations of the compound of the invention may be filled into hard gelatine capsules.

Liquid preparations for oral application may be in the form of syrups or suspensions, for example, solutions containing the compound of the invention, the balance being sugar and a mixture of ethanol, water, glycerol and propylene glycol. Optionally such liquid preparations may contain colouring agents, flavouring agents, saccharine and/or carboxymethylcellulose as a thickening agent or other excipients known to those skilled in art.

The compounds of the invention may also be administered in conjunction with other compounds used for the treatment of the above conditions.

The invention therefore further relates to combination therapies wherein a compound of the invention or a pharmaceutical composition or formulation comprising a compound of the invention is administered concurrently or, sequentially or as a combined preparation with another therapeutic agent or agents, for the treatment of one or more of the conditions listed.

In particular, for the treatment of the inflammatory diseases COPD, asthma and allergic rhinitis the compounds of the invention may be combined with agents such as tumour necrosis factor alpha (TNF-alpha) inhibitors such as anti-TNF monoclonal antibodies (for example Remicade, CDP-870 and adalimumab) and TNF receptor immunoglobulin molecules (such as Enbrel); non-selective cyclo-oxygenase COX-1/COX-2 inhibitors whether applied topically or systemically (such as piroxicam, diclofenac, propionic acids such as naproxen, flubiprofen, fenoprofen, ketoprofen and ibuprofen, fenamates such as mefenamic acid, indomethacin, sulindac, azapropazone, pyrazolones such as phenylbutazone, salicylates such as aspirin), COX-2 inhibitors (such as meloxicam, celecoxib, rofecoxib, valdecoxib, lumarocoxib, parecoxib and etoricoxib); glucocorticosteroids (whether administered by topical, oral, intramuscular, intravenous, or intra-articular routes); methotrexate, lefunomide; hydroxychloroquine, d-penicillamine, auranofin or other parenteral or oral gold preparations.

The present invention still further relates to the combination of a compound of the invention and a leukotriene biosynthesis inhibitor, 5-lipoxygenase (5-LO) inhibitor or 5-lipoxygenase activating protein (FLAP) antagonist such as; zileuton; ABT-761; fenleuton; tepoxalin; Abbott-79175; Abbott-85761; a N-(5-substituted)-thiophene-2-alkylsulfonamide; 2,6-di-tert-butylphenolhydrazones; a methoxytetrahydropyrans such as is Zeneca ZD-2138; the compound SB-210661; a pyridinyl-substituted 2-cyanonaphthalene compound such as L-739,010; a 2-cyanoquinoline compound such as L-746,530; or an indole or quinoline compound such as MK-591, MK-886, and BAY x 1005.

The present invention further relates to the combination of a compound of the invention and a receptor antagonist for leukotrienes (LT B4, LTC4, LTD4, and LTE4) selected from the group consisting of the phenothiazin-3-1s such as L-651,392; amidino compounds such as CGS-25019c; benzoxalamines such as ontazolast; benzenecarboximidamides such as BIIL 284/260; and compounds such as zafirlukast, ablukast, montelukast, pranlukast, verlukast (MK-679), RG-12525, Ro-245913, iralukast (CGP 45715A), and BAY x 7195.

The present invention still further relates to the combination of a compound of the invention and a phosphodiesterase (PDE) inhibitor such as a methylxanthanine including theophylline and aminophylline; a selective PDE isoenzyme inhibitor including a PDE4 inhibitor an inhibitor of the isoform PDE4D, or an inhibitor of PDE5.

The present invention further relates to the combination of a compound of the invention and a histamine type 1 receptor antagonist such as cetirizine, loratadine, desloratadine, fexofenadine, acrivastine, terfenadine, astemizole, azelastine, levocabastine, chlorpheniramine, promethazine, cyclizine, or mizolastine; applied orally, topically or parenterally.

The present invention still further relates to the combination of a compound of the invention and a gastroprotective histamine type 2 receptor antagonist.

The present invention further relates to the combination of a compound of the invention and an antagonist of the histamine type 4 receptor.

The present invention still further relates to the combination of a compound of the invention and an alpha-1/alpha-2 adrenoceptor agonist vasoconstrictor sympathomimetic agent, such as propylhexedrine, phenylephrine, phenylpropanolamine, ephedrine, pseudoephedrine, naphazoline hydrochloride, oxymetazoline hydrochloride, tetrahydrozoline hydrochloride, xylometazoline hydrochloride, tramazoline hydrochloride or ethylnorepinephrine hydrochloride.

The present invention further relates to the combination of a compound of the invention and an anticholinergic agent including muscarinic receptor (M1, M2, and M3) antagonists such as atropine, hyoscine, glycopyrrrolate, ipratropium bromide, tiotropium bromide, oxitropium bromide, pirenzepine or telenzepine.

The present invention still further relates to the combination of a compound of the invention together with a beta-adrenoceptor agonist (including beta receptor subtypes 1-4) such as isoprenaline, salbutamol, formoterol, salmeterol, terbutaline, orciprenaline, bitolterol mesylate, and pirbuterol.

The present invention further relates to the combination of a compound of the invention and a chromone, such as sodium cromoglycate or nedocromil sodium.

The present invention still further relates to the combination of a compound of the invention together with an insulin-like growth factor type I (IGF-1) mimetic.

The present invention still further relates to the combination of a compound of the invention and a glucocorticoid, such as flunisolide, triamcinolone acetonide, beclomethasone dipropionate, budesonide, fluticasone propionate, ciclesonide or mometasone furoate.

The present invention still further relates to the combination of a compound of the invention together with an inhibitor of matrix metalloproteases (MMPs), i.e., the stromelysins, the collagenases, and the gelatinases, as well as aggrecanase; especially collagenase-1 (MMP-1), collagenase-2 (MMP-8), collagenase-3 (MMP-13), stromelysin-1 (MMP-3), stromelysin-2 (MMP-10), and stromelysin-3 (MMP-11) and MMP-9 and MMP-12.

The present invention still further relates to the combination of a compound of the invention together with modulators of chemokine receptor function such as antagonists of CCR1, CCR2, CCR2A, CCR2B, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, CCR10 and CCR11 (for the C-C family); CXCR1, CXCR2, CXCR3, CXCR4 and CXCR5 (for the C-X-C family) and CX3CR1 for the C-X3-C family.

The present invention still further relates to the combination of a compound of the invention together with a cytokine or modulator of cytokine function, including alpha-, beta-, and gamma-interferon; interleukins (IL) including IL1 to 15, and interleukin antagonists or inhibitors, including agents which act on cytokine signalling pathways.

The present invention still further relates to the combination of a compound of the invention together with an immunoglobulin (Ig) or Ig preparation or an antagonist or antibody modulating Ig function such as anti-IgE (omalizumab).

The present invention further relates to the combination of a compound of the invention and another systemic or topically-applied anti-inflammatory agent, such as thalidomide or a derivative thereof, a retinoid, dithranol or calcipotriol.

The present invention further relates to the combination of a compound of the invention together with an antibacterial agent such as a penicillin derivative, a tetracycline, a macrolide, a beta-lactam, a fluoroquinolone, metronidazole, an inhaled aminoglycoside; an antiviral agent including acyclovir, famciclovir, valaciclovir, ganciclovir, cidofovir, amantadine, rimantadine, ribavirin, zanamavir and oseltamavir; a protease inhibitor such as indinavir, nelfinavir, ritonavir, and saquinavir; a nucleoside reverse transcriptase inhibitor such as didanosine, lamivudine, stavudine, zalcitabine or zidovudine; or a non-nucleoside reverse transcriptase inhibitor such as nevirapine or efavirenz.

A compound of the invention can also be used in combination with an existing therapeutic agent for the treatment of cancer, for example suitable agents include:

(i) an antiproliferative/antineoplastic drug or a combination thereof, as used in medical oncology, such as an alkylating agent (for example cis-platin, carboplatin, cyclophosphamide, nitrogen mustard, melphalan, chlorambucil, busulphan or a nitrosourea); an antimetabolite (for example an antifolate such as a fluoropyrimidine like 5-fluorouracil or tegafur, raltitrexed, methotrexate, cytosine arabinoside, hydroxyurea, gemcitabine or paclitaxel); an antitumour antibiotic (for example an anthracycline such as adriamycin, bleomycin, doxorubicin, daunomycin, epirubicin, idarubicin, mitomycin-C, dactinomycin or mithramycin); an antimitotic agent (for example a vinca alkaloid such as vincristine, vinblastine, vindesine or vinorelbine, or a taxoid such as taxol or taxotere); or a topoisomerase inhibitor (for example an epipodophyllotoxin such as etoposide, teniposide, amsacrine, topotecan or a camptothecin);
(ii) a cytostatic agent such as an antioestrogen (for example tamoxifen, toremifene, raloxifene, droloxifene or iodoxyfene), an oestrogen receptor down regulator (for example fulvestrant), an antiandrogen (for example bicalutamide, flutamide, nilutamide or cyproterone acetate), a LHRH antagonist or LHRH agonist (for example goserelin, leuprorelin or buserelin), a progestogen (for example megestrol acetate), an aromatase inhibitor (for example as anastrozole, letrozole, vorazole or exemestane) or an inhibitor of 5Î±-reductase such as finasteride;
(iii) an agent which inhibits cancer cell invasion (for example a metalloproteinase inhibitor like marimastat or an inhibitor of urokinase plasminogen activator receptor function);
(iv) an inhibitor of growth factor function, for example: a growth factor antibody (for example the anti-erbb2 antibody trastuzumab, or the anti-erbb1 antibody cetuximab [C225]), a farnesyl transferase inhibitor, a tyrosine kinase inhibitor or a serine/threonine kinase inhibitor, an inhibitor of the epidermal growth factor family (for example an EGFR family tyrosine kinase inhibitor such as N-(3-chloro-4-fluorophenyl)-7-methoxy-6-(3-morpholinopropoxy)quinazolin-4-amine (gefitinib, AZD1839), N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine (erlotinib, OSI-774) or 6-acrylamido-N-(3-chloro-4-fluorophenyl)-7-(3-morpholinopropoxy)quinazolin-4-amine (CI 1033)), an inhibitor of the platelet-derived growth factor family, or an inhibitor of the hepatocyte to growth factor family;
(v) an antiangiogenic agent such as one which inhibits the effects of vascular endothelial growth factor (for example the anti-vascular endothelial cell growth factor antibody bevacizumab, a compound disclosed in WO 97/22596, WO 97/30035, WO 97/32856 or WO 98/13354), or a compound that works by another mechanism (for example linomide, an inhibitor of integrin Î±vÎ²3 function or an angiostatin);
(vi) a vascular damaging agent such as combretastatin A4, or a compound disclosed in WO 99/02166, WO 00/40529, WO 00/41669, WO 01/92224, WO 02/04434 or WO 02/08213;
(vii) an agent used in antisense therapy, for example one directed to one of the targets listed above, such as ISIS 2503, an anti-ras antisense;
(viii) an agent used in a gene therapy approach, for example approaches to replace aberrant genes such as aberrant p53 or aberrant BRCA1 or BRCA2, GDEPT (gene-directed enzyme pro-drug therapy) approaches such as those using cytosine deaminase, thymidine kinase or a bacterial nitroreductase enzyme and approaches to increase patient tolerance to chemotherapy or radiotherapy such as multi-drug resistance gene therapy; or
(ix) an agent used in an immunotherapeutic approach, for example ex-vivo and in-vivo approaches to increase the immunogenicity of patient tumour cells, such as transfection with cytokines such as interleukin 2, interleukin 4 or granulocyte-macrophage colony stimulating factor, approaches to decrease T-cell anergy, approaches using transfected immune cells such as cytokine-transfected dendritic cells, approaches using cytokine-transfected tumour cell lines and approaches using anti-idiotypic antibodies.

- The present invention will be further explained by reference to the following illustrative examples.

EXPERIMENTAL

Unless otherwise stated organic solutions were dried over magnesium sulphate. RPHPLC means reversed phase preparative HPLC using Waters Symmetry C8, Xterra, or Phenomenex Gemini columns using acetonitrile and either aqueous ammonium acetate, ammonia, formic acid or trifluoroacetic acid as buffer where appropriate. Column chromatography was carried out on silica gel. Treating with SCX means the mixture was absorbed on SCX and eluted with an appropriate solvent such as methanol or acetonitrile then the free base product eluted with aqueous ammonia/methanol.

The present invention will be further explained by reference to the following illustrative examples.

The following abbreviations are used;

EtOAc ethyl acetate
DCM dichloromethane

NMP N-methylpyrrolidineNBS N-bromosuccinamideDMF N,N-dimethylformamide

DMSO dimethylsulfoxide
THF tetrahydrofuran
TFA trifluoroacetic acid
mcpba 3-chloroperoxybenzoic acid (Aldrich 77% max)
rt room temperature
h hours
min minutes
M molar
MS mass spectrometry
APCI atmospheric pressure chemical ionisation
NMR nuclear magnetic resonance
HCl hydrochloric acid
BOC tertiary-butoxycarbonyl
HOBt 1-hydroxybenzotriazole
EDC 1-(3-dimethylamino propyl)-3-ethylcarbodiimide hydrochloride
HATU O-(7-azabenzotriazol-1-yl)-N,N,Nâ€²,Nâ€²-tetramethyluronium hexafluorophosphonate

Unless otherwise stated organic solutions were dried over magnesium sulphate. RPHPLC denotes Reverse Phase Preparative High Performance Liquid Chromatography using Waters Symmetry C8, Xterra or Phenomenex Gemini columns using acetonitrile and either aqueous ammonium acetate, ammonia, formic acid or trifluoroacetic acid as buffer where appropriate. Column chromatography was carried out on silica gel.

Example 16-Amino-2-butoxy-9-(3-pyrrolidin-1-ylpropyl)-7,9-dihydro-8H-purin-8-one

(i) 2-Chloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-amine

2,6-Dichloro-9-(tetrahydro-2H-pyran-2-yl)-9H-purine (55 g) was dissolved in 7N-aqueous ammonia in MeOH (500 ml) and heated at 100Â° C. in a sealed flask for 6 h. The reaction mixture was cooled to rt and left overnight. Filtration afforded the subtitle compound. Yield 40 g.

¹H NMR Î´ (CDCl₃) 8.02 (1H, s), 5.94 (2H, brs), 5.71 (1H, dd), 4.15-4.22 (1H, m), 3.75-3.82 (1H, m), 1.27-2.12 (6H, m).

(ii) 2-Butoxy-9-(tetrahydro-2H-pyran-2-yl)-9H-purin-6-amine

The product from step (i) (40 g) was dissolved in 19% (w/w)-sodium butoxide in butanol (250 ml). The reaction mixture was stirred under reflux for 6 h. The resultant suspension was cooled to rt, diluted with water and extracted with diethyl ether. The combined organic phase was washed with water, dried and concentrated in vacuo. The subtitle compound was crystallised from diethyl ether/isohexane (1/1, 300 ml) and obtained by filtration. Yield 19 g.

¹H NMR Î´ (CDCl₃) 7.87 (1H, s), 5.56-5.68 (3H, m), 4.31-4.35 (2H, t), 4.14-4.17 (1H, m), 3.76-3.80 (1H, m), 1.49-2.08 (10H, m), 0.98 (3H, t).

(iii) 8-Bromo-2-butoxy-9-(tetrahydro-2H-pyran-2-yl) 9H-purin-6-amine

The product from step (ii) (30 g) was dissolved in dry dichloromethane (200 ml). The solution was stirred at rt whilst NBS (27 g) was added portionwise. The mixture was stirred at rt overnight. 20% (w/v)-Sodium sulfate (200 ml) was added and the separated aqueous phase extracted with DCM. The combined organic phase was washed with saturated sodium hydrogen carbonate solution and brine. After concentration in vacuo, the residue was dissolved in ethyl acetate, washed with water, brine and dried. The solution was filtered through silica gel and concentrated in vacuo. The residue was triturated with diethyl ether and isohexane (1/1, 200 ml) then filtered to give the subtitle compound (26 g). The filtrate was concentrated in vacuo and the residue purified by column chromatography (ethyl acetate/isohexane) to give a further 2.5 g of product. The solids were combined to give the subtitle compound as a yellow solid. Yield 28.5 g. mp 148-50Â° C.

¹H NMR Î´ (CDCl₃) 5.59-5.64 (3H, m), 4.32 (2H, m), 4.17 (1H, m), 3.74 (1H, m), 3.08 (1H, m), 2.13 (1H, d), 1.48-1.83 (8H, m), 0.98 (3H, t).

(iv) 2-Butoxy-8-methoxy-9-(tetrahydro-2H-pyran-2-yl) 9H-purin-6-amine

Sodium (3.7 g) was added to absolute MeOH (400 ml) under a nitrogen atmosphere. To this solution was added the product from step (iii) (28.5 g) and the mixture was stirred at 65Â° C. for 9 h. The mixture was concentrated in vacuo and 500 ml of water added. The aqueous phase was extracted with ethyl acetate, washed with brine and dried. The subtitle compound was obtained after crystallisation from diethyl ether. Yield 14.2 g.

¹H NMR Î´ (CDCl₃) 5.51 (1H, dd), 5.28 (2H, brs), 4.29 (2H, t), 4.11-4.14 (4H, m), 3.70 (1H, m), 2.76-2.80 (1H, m), 2.05 (1H, d), 1.47-1.81 (8H, m), 0.97 (3H, t).

(v) 2-Butoxy-8-methoxy-9H-purin-6-amine, TFA salt

The product from step (iv) (24 g) was dissolved in absolute MeOH (300 ml) and 30 ml of TFA was added. The reaction mixture was stirred at rt for 3 days and concentrated in vacuo. The subtitle compound was obtained as a white crystalline solid after trituration with MeOH/ethyl acetate. Yield 21 g.

¹H NMR Î´ (CD₃OD) 4.48 (2H, t), 4.15 (3H, s), 1.80 (2H, quintet), 1.50 (2H, sextet), 0.99 (3H, t).

(vi) 9-(3-Chloropropyl)-2-butoxy-8-methoxy-9H-purin-6-amine

The product of step (v) (50 g) was added in portions over 10 minutes to a rapidly stirred mixture of potassium carbonate (60 g) and 1-bromo-3-chloropropane (21 ml) in DMF (400 ml) at rt and the mixture stirred for 3 h. The mixture was diluted with water and extracted with ethyl acetate. The combined extracts were washed with water and dried. The crude product was recrystallised from acetonitrile. Yield 29.83 g.

MS:ESI (+ve): 314

(vii) 6-Amino-9-(3-chloropropyl)-2-butoxy-7,9-dihydro-8H-purin-8-one

The product of step (vi) (29.8 g) was dissolved in MeOH (60 ml) and treated with 4M hydrogen chloride in dioxane (60 ml). The mixture was stirred at rt for 2 hours, cooled to 0Â° C. and neutralised with 3.5% aqueous ammonia solution. The solid was filtered off, washed with water then MeOH and dried Yield 27.2 g.

¹H NMR 6 (DMSO-d₆) 9.88 (1H, s), 6.41 (2H, t), 4.15 (2H, t), 3.80 (2H, t), 3.65 (2H, t), 2.14-2.07 (2H, m), 1.68-1.61 (2H, m), 1.43-1.34 (2H, m), 0.92 (3H, t).

(viii) 6-Amino-2-butoxy-9-(3-pyrrolidin-1-ylpropyl)-7,9-dihydro-8H-purin-8-one

The product from step (vii) (0.15 g) was dissolved in DMSO (2 mL) and pyrrolidine (0.18 g) was added. The reaction mixture was stirred at rt for 16 h. The reaction mixture was filtered through a filter disc and purified via RP-prep-HPLC to give title compound (0.044 g).

¹H NMR Î´ (DMSO-d₆) 9.83 (1H, s), 6.37 (2H, s), 4.15 (2H, t), 3.71 (2H, t), 2.41-2.30 (6H, m), 1.84-1.73 (2H, m), 1.69-1.58 (6H, m), 1.43-1.32 (2H, m), 0.92 (3H, t)

MS:ESI (+ve): 335

Examples 2-4 were made by the same method as example 1 using the appropriate amine:

Example 21-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]-N,N-dimethyl-L-prolinamide

¹H NMR 6 (DMSO-d₆) 9.82 (1H, s), 6.38 (2H, s), 4.14 (2H, t), 3.82-3.68 (1H, m), 3.68-3.54 (1H, m), 3.48-3.35 (1H, m), 3.10-2.97 (4H, m), 2.77 (3H, s), 2.35-2.21 (4H, m), 2.04-1.91 (2H, m), 1.80-1.58 (5H, m), 1.45-1.31 (2H, m), 0.92 (3H, t)

MS:APCI (+ve): 406

Example 36-Amino-2-butoxy-9-{3-[(25)-2-(methoxymethyl)pyrrolidin-1-yl]propyl}-7,9-dihydro-8H-purin-8-one

¹H NMR 6 (DMSO-d₆) 9.81 (1H, s), 6.37 (2H, s), 4.15 (2H, t), 3.77-3.57 (2H, m), 3.30-3.23 (1H, m), 3.19 (3H, s), 3.11-2.98 (2H, m), 2.86-2.74 (1H, m), 2.48-2.41 (1H, m), 2.30-2.18 (1H, m), 2.09-1.97 (1H, m), 1.84-1.72 (3H, m), 1.69-1.55 (4H, m), 1.47-1.33 (3H, m), 0.92 (3H, t)

MS:APCI (+ve): 379

Example 4N²-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]-N¹,N¹,N²-trimethylglyeinamide

¹H NMR Î´ (DMSO-d₆) 9.83 (1H, s), 6.38 (2H, s), 4.14 (2H, t), 3.68 (2H, t), 3.13 (2H, s), 3.00 (3H, s), 2.78 (3H, s), 2.39 (2H, t), 2.18 (3H, s), 1.82-1.72 (2H, m), 1.69-1.58 (2H, m), 1.44-1.33 (2H, m), 0.91 (3H, t)

MS:APCI (+ve): 380

Example 51-[3-(6-Amino-2-butoxy-8-oxo-7,8-dihydro-9H-purin-9-yl)propyl]pyrrolidine-2,5-dione

The product from example 1 step (vii) (0.15 g) was dissolved in DMSO (2 mL) and succinimide (0.25 g) and potassium carbonate (0.07 g) was added. The reaction mixture stirred at 60Â° C. for 16 h. The reaction mixture was filtered through a filter disc and purified via RP-prep-HPLC to give title the compound (0.065 g)

¹H NMR 8 (DMSO-d₆) 6.41 (2H, s), 4.14 (2H, t), 3.66 (2H, t), 3.40-3.33 (2H, m), 2.58 (4H, s), 1.93-1.82 (2H, m), 1.69-1.58 (2H, m), 1.44-1.34 (2H, m), 0.92 (3H, t)

MS:ESI (+ve): 363

Examples 6 and 7 were made by the same method as example 5 using the appropriate amine:

Example 66-Amino-2-butoxy-9-(3-{[(1S)-2-methoxy-1-methylethyl]amino}propyl)-7,9-dihydro-8H-purin-8-one

¹H NMR 6 (DMSO-d₆) 6.40 (2H, s), 4.15 (2H, t), 3.70 (2H, t), 3.31 (3H, s), 3.21 (3H, s), 3.19-3.04 (2H, m), 2.74-2.62 (1H, m), 1.79-1.56 (4H, m), 1.45-1.31 (2H, m), 0.96-0.82 (6H, m)

MS:ESI (+ve): 353

Example 76-Amino-2-butoxy-9-{3-[methyl-(2-morpholin-4-yl-2-oxo-ethyl)-amino]-propyl}-7,9-dihydro-purin-8-one

¹H NMR Î´ (DMSO-d₆) 9.83 (1H, s), 6.38 (2H, s), 4.14 (2H, t), 3.73-3.60 (2H, m), 3.60-3.47 (5H, m), 3.45-3.37 (2H, m), 3.12 (2H, d), 2.41-2.24 (3H, m), 2.17 (3H, s), 1.84-1.72 (2H, m), 1.69-1.56 (2H, m), 1.44-1.32 (2H, m), 0.91 (3H, t)

MS:ESI (+ve): 422

Example 8Biological Assay

Human TLR7 assay

Recombinant human TLR7 was stably expressed in a HEK293 cell line already stably expressing the pNiFty2-SEAP reporter plasmid; integration of the reporter gene was maintained by selection with the antibiotic zeocin. The most common variant sequence of human TLR7 (represented by the EMBL sequence AF240467) was cloned into the mammalian cell expression vector pUNO and transfected into this reporter cell-line. Transfectants with stable expression were selected using the antibiotic blasticidin. In this reporter cell-line, expression of secreted alkaline phosphatase (SEAP) is controlled by an NFkB/ELAM-1 composite promoter comprising five NFkB sites combined with the proximal ELAM-1 promoter. TLR signaling leads to the translocation of NFkB and to activation of the promoter results in expression of the SEAP gene. TLR⁷-specific activation was assessed by determining the level of SEAP produced following overnight incubation of the cells at 37Â° C. with the standard compound in the presence of 0.1% (v/v) dimethylsulfoxide (DMSO). Concentration dependent induction of SEAP production by compounds was expressed as the concentration of compound which produced half of the is maximal level of SEAP induction for that compound (pEC₅₀)

Compound of Example:1pEC₅₀6.42pEC₅₀5.53pEC₅₀5.64pEC₅₀6.6