WO1996002543A1 - 2,3-dihydroxy cyclopentane derivatives of purines - Google Patents

Abstract

2,3-dihydroxy cyclopentane derivatives are described having general formula (I) and salts and solvates thereof, wherein: R1 is hydrogen, C¿3-8?cycloalkyl or C1-6alkyl; R?2¿ is C¿3-8? cycloalkyl, C3-8cycloalkylC1-6alkyl, Alk1Y, -(CHR?5)¿m(Alk2)nZ or appropriately substituted C3-8cycloalkyl, C3-8cycloalkylC1-6alkyl, pyrrolidin-3-yl, 2-oxopyrrolidin-4-yl, 2-oxopyrrolidin-5-yl, piperidin-3-yl or piperidin-4-yl, and Q is oxygen or sulphur. Compounds of formula (I) and their salts and solvates have use in medicine as anti-inflammatory agents, particularly in the treatment of patients with inflammatory conditions who are susceptible to leukocyte-induced tissue damage.

Description

2,3-DIHYDROXY CYCLOPENTANE DERIVATIVES OF PURINES

The present invention relates to therapeutically active substituted 2,3- dihydroxy cyclopentane derivatives, processes for the manufacture of said compounds, pharmaceutical formulations containing said compounds and the use of said compounds in chemotherapy. In particular, we have found a group of novel compounds which are effective in treating inflammatory diseases.

Inflammation is a primary response to tissue injury or microbial invasion and is

10 characterised by circulating leukocytes binding to and extravasion through vascular endothelium. Circulating leukocytes include neutrophils, eosinophils, basophils, monocytes and lymphocytes. Different forms of inflammation involve different types of infiltrating leukocytes, the particular profile being regulated by gene expression in vascular endothelium in response to a variety

15 of inflammatory mediators.

The primary function of leukocytes is to defend the host from invading organisms such as bacteria and parasites. Once a tissue is injured or infected

HO OH and salts and solvates thereof, wherein: R¹ represents a hydrogen atom or a C3_8cycloalkyl or C^al yl group; R2 represents a group selected from

(') C3_βcycloalkyl

(ϋ) C3_8cycloalkyl substituted by one or more groups (e.g. 1 , 2 or 3 groups) which may be the same or different and are selected from C2_7acylamino, guanidino, carboxyl, oxo and (CH2)pR³ (where p is zero or 1 and R³ is hydroxy, NH2,

or diC-j-ealkylamino)

(iii) pyrrolidin-3-yl, 2-oxopyrrolidin-4-yl, 2-oxopyrrolidin-5-yl, piperidin-3-yl or piperidin-4-yl in which the ring nitrogen atom is substituted by hydrogen, C*|_6alkyl or arylC*ι_6alkyl (e.g. benzyl) (iv) pyrrolidin-3-yl, piperidin-3-yl or piperidin-4-yl in which the ring nitrogen atom is substituted by hydrogen, C<|_6alkyl or arylC-j^alkyl (e.g. benzyl) and one or more of the ring carbon atoms (e.g. 1, 2 or 3 ring carbon atoms) is substituted by the same or different groups selected from C2-7acylamino, guanidino, oxo and (CH2)p ³ (where p and R³ are as defined previously) (v) C3_8cycloalkylC^<|_6alkyl (vi) C3_8cycloalkylC*ι ^alkyl in which one or more of the ring carbon atoms

(e.g. 1 , 2 or 3 ring carbon atoms) is substituted by the same or different groups selected from C2-7acylamino, guanidino, carboxyl, oxo and (CH2)pR³ (where p and R³ are as defined previously) (vii) -Alk-_|Y where Alk-j is a C2-6 alkylene group and Y is a group selected from C2-7acylamino, guanidino, hydroxyl, NH2, C-j-βalkylamino, diC-_|_6alkylamino or / \

^■N X

\ /

(where X is a bond, 0, CH2 or NR⁴ in which R⁴ is hydrogen, C-j^alkyl or arylC*|_6alkyl) and

(viii) -(CHRⁱ-⁵)_m(Alk2)nZ where m and n each independently represent zero or 1 except that when m is 1 then n must also represent 1 , R^ is a hydrogen atom or a carboxy group or a group CH2R⁶ (where R⁶ is C2-7acylamino, guanidino, hydroxy, methoxy, NH2,

Alk2 is a C-j.

5alkylidene group and Z is a hydrogen atom or an optionally substituted aromatic ring selected from phenyl, pyridyl, pyrimidinyl, imidazolyl, triazolyl, tetrazolyl and benzimidazolyl where the ring is optionally substituted by one or more groups (e.g. 1, 2 or 3 groups) which may be the same or different and are selected from C-j-βalkyl, C2-7acylamino, guanidino, carboxyC^alkyl, hydroxy,

NH2, C<|_6alkylamino or

Q represents an oxygen or sulphur atom; and Ph represents phenyl.

Suitable salts of the compounds of formula (I) include physiologically acceptable salts such as acid addition salts derived from inorganic or organic acids, for example hydrochlorides, hydrobromides, sulphates, phosphates, acetates, benzoates, citrates, succinates, lactates, tartrates, fumarates and maleates, and, if appropriate, inorganic base salts such as alkali metal salts, for example sodium salts. Other salts of the compounds of formula (I) include salts which are not physiologically acceptable but may be useful in the preparation of compounds of formula (I) and physiologically acceptable salts thereof. Examples of such salts include trifluoroacetates.

Examples of suitable solvates of the compounds of formula (I) include hydrates.

It will be appreciated that when R² in compounds of formula (I) contains one or more asymmetric carbon atoms the invention includes all diastereoisomers of compounds of formula (I) and mixtures thereof. Otherwise, the stereochemical configuration of compounds of the invention is as depicted in formula (I) above. It is to be understood that all tautomeric forms of the compounds of formula (I) are included within the scope of this invention.

The cycloalkyl group within R1 or R2 may be a monocydic or bridged cyclic ring. Particular examples of suitable cycloalkyl ring systems include C3.8 monocydic cycloalkyl groups such as cyclopropyl, cyclopentyl and cyclohexyl. Within R² the C3_s cycloalkyl group may particularly represent cyclopentyl or cyclohexyl.

The term 'aryl' as part of an

group may represent, for example, a phenyl group optionally substituted by one or more substituents (e.g. 1 , 2 or 3 substituents) which may be the same or different and are selected from halogen, hydroxyl, C*i-3alkoxy and Cι_3alkyl.

The term 'alkyl' as a group or part of a group means a straight or branched chain alkyl group. Particular examples of suitable alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl and t-butyl.

The term 'alkylene' as part of a group means a straight or branched alkylene chain. Particular examples of suitable alkylene chains include -CH2-, -CH2CH2-, -CH2CH2CH2-, -CHCH3CH2- and -CH₂C(CH3)₂CH₂-.

When R2 represents a group -Alk*ιY the C2-6alkylene group may particularly represent -CH2CH2-, -CH2CH2CH2- or -CH₂C(CH3)₂CH2-.

When R² represents a group -(CHR⁵)_m(Alk2)_nZ the chain -(CHR⁵)_m(Alk2)_n- may particularly represent a bond, -CH2-, -CH2CH2-, -CHR⁵CHCH3CH2- or -CHR⁵CH2- (where R⁵ is a group CH2R⁶ and R⁶ is as defined previously).

The term 'C2-7acylamino' within R² means a C2-7alkanoylamino group wherein the C-i-βalkyl portion thereof is a straight or branched alkyl group as previously defined and may be optionally substituted by one or more halogen atoms such as fluorine. Examples of suitable C2-7alkanoylamino groups within R² include acetamido and trifluoroacetamido. Within Z, the term 'pyridyl' means a 2-, 3- or 4-pyridyl group; the term 'pyrimidinyl' means a 2-, 4- or 5-pyrimidinyl group; the term 'imidazolyl^* means a 1-.2- 4- or 5-imidazolyl group; and the term 'triazolyl' means a 1 , 2, 4-triazolyl group (e.g. 1, 2, 4-thazol-l-yl or 1 , 2, 4-triazol-3-yl).

R^"- preferably represents a C*]_3alkyl group, especially ethyl.

Compounds of formula (I) in which Q represents an oxygen atom are generally preferred.

Compounds of formula (I) in which R¹ NHC(=Q)- represents ethylaminocarbonyl are particularly preferred.

A preferred group of compounds of the invention are compounds of formula (I) in which R² represents a substituted cyclopentyl or cyclohexyl group wherein the ring is substituted by one or two groups, especially one or two groups selected from hydroxy, Nh , methylamino, dimethylamino, acetamido or trifluoroacetamido. Preferred substituents include hydroxy, NH₂ and dimethylamino.

A further preferred group of compounds of the invention are compounds of formula (I) in which R² represents a pyrrolidin-3-yl or piperidin-3-yl group in which the ring nitrogen atom is substituted by hydrogen, Cι_3alkyl (e.g. ethyl) or benzyl.

Another preferred group of compounds of the invention are compounds of formula (I) in which R² represents (CHR⁵)_m(Alk2)_nZ where R⁵, m and n are as defined previously and Z is an optionally substituted imidazolyl group. Particularly preferred are those compounds in which -(CH2R^) (Alk2)n- represents -CH2CH2-.

Yet a further preferred group of compounds of the invention are compounds of formula (I) in which R² is Alk-, Y where Alki is a C₂alkylene group and Y is / \

N X

\ /

(where X is a bond, O, CH₂).

It is to be understood that the present invention covers all combinations of particular and preferred groups referred to hereinabove.

Specific compounds of the present invention include: (1 S,2R,3S,4R)-4-[trans-2-(4-Amino-cyclohexylamino)-6-(2,2-diphenyl- ethylamino)-purin-9-yl]-2,3-dihydroxy-cyclopentanecarboxylic acid ethylamide;

(1S,2R,3S,4R)-4-[6-(2,2-Diphenyl-ethylamino)-2-[2-(pipehdin-1-yl)-ethylamino]- purin-9-yl]-2,3-dihydroxy-cyclopentanecarboxylic acid ethylamide;

(1 S,2R,3S,4R)-4-[6-(2,2-Diphenyl-ethylamino)-2-[2-(1-methyl-1 H-imidazol-4- yl)-ethylamino]-purin-9-yl]-2,3-dihydroxy-cyclopentanecarboxylic acid ethylamide; and

and physiologically acceptable salts and solvates thereof.

The potential for compounds of formula (I) to inhibit leukocyte function may be demonstrated, for example, by their ability to inhibit superoxide (O2") generation from neutrophils stimulated with chemoattractants such as N- formylmethionyl-leucyl-phenylalanine (fMLP). Accordingly, compounds of formula (I) are of potential therapeutic benefit in providing protection from leukocyte-induced tissue damage in diseases where leukocytes are implicated at the site of inflammation.

Examples of disease states in which the compounds of the invention have potentially beneficial anti-inflammatory effects include diseases of the respiratory tract such as adult respiratory distress syndrome (ARDS), bronchitis (including chronic bronchitis), cystic fibrosis, asthma (including allergen-induced asthmatic reactions), emphysema, rhinitis and septic shock. Other relevant disease states include diseases of the gastrointestinal tract such as intestinal inflammatory diseases including inflammatory bowel disease (e.g. Crohn's disease or ulcerative colitis), Helicobacter-pylori induced gastritis and intestinal inflammatory diseases secondary to radiation exposure or allergen exposure, and non-steroidal anti-inflammatory drug-induced gastropathy. Furthermore, compounds of the invention may be used to treat skin diseases such as psoriasis, allergic dermatitis and hypersensitivity reactions.

Further examples of disease states in which compounds of the invention have potentially beneficial effects include cardiac conditions such as peripheral vascular disease, post-ischaemic reperfusion injury and idiopathic hypereosinophilic syndrome.

Compounds of the invention which inhibit lymphocyte function also have use in the treatment of auto-immune diseases such as rheumatoid arthritis and diabetes.

Compounds of the invention may also be useful in inhibiting metastasis.

It will be appreciated by those skilled in the art that reference herein to treatment extends to prophylaxis as well as the treatment of established conditions.

As mentioned above, compounds of formula (I) are useful in human or veterinary medicine, in particular as anti-inflammatory agents.

There is thus provided as a further aspect of the invention a compound of formula (I) or a physiologically acceptable salt or solvate thereof for use in human or veterinary medicine, particularly in the treatment of patients with inflammatory conditions who are susceptible to leukocyte-induced tissue damage.

According to another aspect of the invention, there is provided the use of a compound of formula (I) or a physiologically acceptable salt or solvate thereof for the manufacture of a medicament for the treatment of patients with inflammatory conditions who are susceptible to leukocyte-induced tissue damage.

In a further or alternative asped there is provided a method for the treatment of a human or animal subjed with an inflammatory condition who is susceptible to leukocyte-induced tissue damage, which method comprises administering to said human or animal subject an effective amount of a compound of formula (I) or a physiologically acceptable salt or solvate thereof.

The compounds according to the invention may be formulated for administration in any convenient way, and the invention therefore also includes within its scope pharmaceutical compositions for use in anti-inflammatory therapy, comprising a compound of formula (I) or a physiologically acceptable salt or solvate thereof together, if desirable, with one or more physiologically acceptable carriers or excipients.

The compounds according to the invention may, for example, be formulated for oral, buccal, parenteral, topical or rectal administration, preferably for parenteral or topical (e.g. by aerosol) administration.

Tablets and capsules for oral administration may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, mucilage of starch, cellulose or polyvinyl pyrrolidone; fillers, for example, lactose, microcrystalline cellulose, sugar, maize- starch, calcium phosphate or sorbitol; lubricants, for example, magnesium stearate, stearic acid, talc, polyethylene glycol or silica; disintegrants, for example, potato starch, croscarmellose sodium or sodium starch glycollate; or wetting agents such as sodium lauryl sulphate. The tablets may be coated according to methods well known in the art. Oral liquid preparations may be in the form of, for example, aqueous or oily suspensions, solutions, emulsions, syrups or elixirs, or may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example, sorbitol syrup, methyl cellulose, glucose/sugar syrup, gelatin, hydroxymethyl cellulose, carboxymethyl cellulose, aluminium stearate gel or hydrogenated edible fats; emulsifying agents, for example, lecithin, sorbitan mono-oleate or acacia; non- aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters, propylene glycol or ethyl alcohol; or preservatives, for example, methyl or propyl β- hydroxybenzoates or sorbic acid. The preparations may also contain buffer salts, flavouring, colouring and/or sweetening agents (e.g. mannitol) as appropriate.

For buccal administration the compositions may take the form of tablets or lozenges formulated in conventional manner.

The compounds may also be formulated as suppositories, e.g. containing conventional suppository bases such as cocoa butter or other glycerides.

The compounds according to the invention may also be formulated for parenteral administration by bolus injection or continuous infusion and may be presented in unit dose form, for instance as ampoules, vials, small volume infusions or pre-filled syringes, or in multi-dose containers with an added preservative. The compositions may take such forms as solutions, suspensions, or emulsions in aqueous or non-aqueous vehicles, and may contain formulatory agents such as anti-oxidants, buffers, antimicrobial agents and/or tonicity adjusting agents. Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g. sterile, pyrogen-free water, before use. The dry solid presentation may be prepared by filling a sterile powder aseptically into individual sterile containers or by filling a sterile solution aseptically into each container and freeze-drying.

By topical administration as used herein, we include administration by insufflation and inhalation. Examples of various types of preparation for topical administration include ointments, creams, lotions, powders, pessaries, sprays, aerosols, capsules or cartridges for use in an inhaler or insufflator, solutions for nebulisation or drops (e.g. eye or nose drops).

Ointments and creams may, for example, be formulated with an aqueous or oily base with the addition of suitable thickening and/or gelling agents and/or solvents. Such bases may thus, for example, include water and/or an oil such as liquid paraffin or a vegetable oil such as arachis oil or castor oil or a solvent such as a polyethylene glycol. Thickening agents which may be used include soft paraffin, aluminium stearate, cetostearyl alcohol, polyethylene glycols, microcrystalline wax and beeswax.

Lotions may be formulated with an aqueous or oily base and will in general also contain one or more emulsifying agents, stabilising agents, dispersing agents, suspending agents or thickening agents.

Powders for external application may be formed with the aid of any suitable powder base, for example, talc, lactose or starch. Drops may be formulated with an aqueous or non-aqueous base also comprising one or more dispersing agents, solubilising agents or suspending agents.

Spray compositions may be formulated, for example, as aqueous solutions or suspensions or as aerosols delivered from pressurised packs, with the use of a suitable propellant, e.g. dichlorodifluoromethane, trichlorofluoromethane, dichlorotetra-fluoroethane, 1 ,1 ,1 ,2,3,3,3-heptafluoropropane, 1,1,1,2- tetrafluorethane, carbon dioxide or other suitable gas.

Intranasal sprays may be formulated with aqueous or non-aqueous vehicles with the addition of agents such as thickening agents, buffer salts or acid or alkali to adjust the pH, isotonicity adjusting agents or anti-oxidants.

Capsules and cartridges of for example gelatin, or blisters of for example laminated aluminium foil, for use in an inhaler or insufflator may be formulated containing a powder mix of a compound of the invention and a suitable powder base such as lactose or starch.

Solutions for inhalation by nebulation may be formulated with an aqueous vehicle with the addition of agents such as acid or alkali, buffer salts, isotonicity adjusting agents or antimicrobials. They may be sterilised by filtration or heating in an autoclave, or presented as a non-sterile product. The pharmaceutical compositions according to the invention may also be used in combination with other therapeutic agents, for example anti-inflammatory agents such as corticosteroids or NSAIDs.

The invention thus provides, in a further aspect, a combination comprising a compound of formula (I) or a physiologically acceptable salt or solvate thereof together with another therapeutically active agent, for example an anti- inflammatory agent such as a corticosteroid or NSAID.

The combination referred to above may conveniently be presented for use in the form of a pharmaceutical formulation and thus pharmaceutical formulations comprising a combination as defined above together with a pharmaceutically acceptable carrier thereof represent a further aspect of the invention.

The individual components of such combinations may be administered either sequentially or simultaneously in separate or combined pharmaceutical formulations. Appropriate doses of known therapeutic agents will be readily appreciated by those skilled in the art.

Compounds of the invention may conveniently be administered in amounts of, for example, 0.01 to 500mg/kg body weight, preferably 0.01 to 100mg/kg body weight, 1 to 4 times daily. The precise dose will of course depend on the age and condition of the patient and the particular route of administration chosen.

The compounds of formula (I) and salts and solvates thereof may be prepared by the methodology described hereinafter, constituting a further aspect of this invention. In the following procedures, the groups R¹, R² and Q are as defined for compounds of formula (I) unless otherwise stated.

Thus, according to first process (A), a compound of formula (I) may be prepared by treating a compound of formula (II)

OR^* OR^b

(wherein R^a and R*³ each represent a hydrogen atom or together form an alkylidene group such as isopropylidene) with an amine R2a|siH2 (wherein R2a is a group R or is a protected derivative thereof), followed, where necessary, by the removal of any protecting groups present.

The displacement reaction to introduce the amine moiety may be carried out by heating the reagents at a temperature in the range of 50^u to 150^0 optionally in the presence of a solvent such as dimethylsulphoxide.

A compound of formula (II) in which Q represents a sulphur atom may be prepared from a compound of formula (II) in which Q represents an oxygen atom and R^a and R^D together form an alkylidene group such as isopropylidene by thianation followed, if appropriate, by the removal of the alkylidene group.

The thianation readion may be conveniently effected using known thianation agents such as hydrogen sulphide, phosphorus pentasulphide or Lawesson's reagent (p-methoxyphenylthiophosphine sulphide dimer). The readion may be carried out in a known manner. For example when hydrogen sulphide is used an acid such as hydrochloric acid may conveniently be added in catalytic amounts and the reaction carried out in a polar solvent such as acetic acid or ethanol. When using Lawesson's reagent, the readion may conveniently be carried out in a dry solvent such as toluene or methylene chloride.

A compound of formula (II) in which Q represents an oxygen atom may be prepared by treating a compound of formula (III)

OR^* OR"

(wherein R^a and R^D are as defined previously) with 2,2-diphenylethylamine, preferably in the presence of a base such as an amine base (e.g. diisopropylethylamine) and in a solvent such as an alcohol (e.g. isopropanol) at an elevated temperature (e.g. reflux), followed if desired by removing any protecting groups present.

Compounds of formula (III) may be obtained from intermediates of formula (IV)

OR* OR^b

(wherein R¹, R^a and R^b are as previously defined) by reaction with a compound of formula (R^cO)₃ CH (where R^c represents C_halky!) under acidic conditions, followed by heating at, for example, about 100-120°C, followed if desired by removing any protecting groups present.

Alternatively, compounds of formula (II) may be prepared from compounds of formula (IV) by reaction with a compound of formula (R^cO)₂CH0₂CR^d (where R^c and R^d each independently represents C₁_ alkyl) followed by readion with 2,2-diphenylethylamine, preferably in the presence of a base as previously described followed if desired by removing any protecting groups present.

Compounds of formula (IV) may be prepared by reaction of compounds of formula (V)

OR^* OR^b

(wherein R¹, R^a and R^b are as previously defined) with 5-amino-2,4,6- trichloropyrimidine in the presence of a base.

Suitable bases for use in the reaction include tertiary amines such as, for example, triethylamine. The reaction is conveniently effected in a suitable organic solvent, such as an alcohol, for example, butanol, preferably at elevated temperature, such as the reflux temperature of the chosen solvent.

Compounds of formula (V) may be prepared by any of the methods known in the art for the preparation of compounds of analogous structure. For example, according to one method, compounds of formula (V) may be prepared from intermediates of formula (VI)

OR¹ OR by reaction with an amine of formula R¹NH₂ at elevated temperature and pressure.

The reaction is suitably conducted in a bomb heated to about 150-160°C. Compounds of formula (VI) may be prepared by hydroxylation of the known compound of formula (VII)

followed by introduction of protecting groups R^a and R^b, if required.

A compound of formula (II) in which Q represents an oxygen atom may also be prepared by treating a compound of formula (VIII)

OR⁴ OR^b

(wherein R^a and R*³ are as defined previously) or an active derivative thereof such as a corresponding mixed anhydride with an amine R¹ NH2, followed if desired by removing any protecting groups present.

The amination reaction may be effeded in known manner, for example by adding the amine in a solvent sμch as a halogenated hydrocarbon (e.g. methylene chloride) or in dimethylformamide, in the presence of an amine such as triethylamine at about 0° to 20°C to the compound (VIII) or, more particularly, a corresponding mixed anhydride. The mixed anhydride may be prepared, for example, by treating compound (VIII) with pivaloyl chloride, conveniently at about 0°C.

A compound of formula (VIII) may be prepared by oxidising a compound of formula (IX)

OR^* OR or a salt thereof (wherein R^a and R^D together form an alkylidene group such as isopropylidene), followed if desired by removing the alkylidene group. The oxidation reaction may be effected in known manner using an oxidising agent such as potassium permanganate or pyridinium dichromate, or, preferably, ruthenium trichloride in the presence of sodium periodate .

Compounds of formula (IX) wherein R^a and R^b represent an alkylidene group may be prepared from the corresponding compounds of formula (IX) wherein R^a and R^b each represent H by conventional methods.

A compound of formula (IX) wherein R^a and R^b each represents H may be prepared by treating a compound of formula (X)

OR OR (wherein R^p is a suitable hydroxyl protecting group, such as an acyl group) with 2,2-diphenylethylamine under the conditions described previously for preparing compounds of formula (II) from compounds of formula (III), followed by removal of the protecting groups R^p in conventional manner.

Compounds of formula (X) may be prepared from compounds of formula (XI)

OR OR

by reaction with a suitable chlorinating agent, such as pyridine hydrochloride in the presence of copper (I) chloride and t-butyl nitrite.

Compounds of formula (XI) may be prepared from compounds of formula (XII)

)R' ' OR^p by reaction with phosphorous oxychloride under conventional conditions.

Compounds of formula (XII) are known compounds or may be prepared from known compounds by conventional procedures readily appreciated by those skilled in the art.

The amines R2aNH2 are either known in the art or may be prepared by the methods described in the Examples Section hereinafter or by methods analogous to such methods hereinafter. Compounds of formulae (II), (VIII), (IX) and (X), are novel intermediates and represent further aspeds of the present invention. Compounds of formula (II) in which R^a and R^D represent hydrogen atoms are also adive compounds in their own right and constitute a further particular aspect of the present invention.

It will be appreciated that in addition to 2,3-diol groups, groups present within R may need to be protected, and deprotection may be required as an intermediate or final step to yield the desired compound. Thus, according to another general process (B), a compound of formula (I) may be prepared by subjecting a protected derivative of a compound of formula (I) to readion to remove the proteding group or groups. Protedion and deprotection of functional groups may be effeded using conventional means. Thus, for example, amino groups may be protected by a group selected from aralkyl (e.g. benzyl), acyl (e.g. benzyloxycarbonyl or t-butoxycarbonyl) or sulphonyl (e.g. allylsulphonyl or tosyl); subsequent removal of the protecting group being effected when desired by hydrolysis or hydrogenolysis as appropriate using standard conditions. Hydroxyl groups may be proteded using any conventional hydroxyl protecting group, for example, as described in "Protedive Groups in Organic Chemistry", Ed. J.F.W. McOmie (Plenum Press,

1973) or "Protective Groups in Organic Synthesis" by Theodora W. Greene and P.G.M. Wuts (John Wiley and Sons, 1991 ). Examples of suitable hydroxyl protecting groups include groups selected from alkyl (e.g. methyl, t-butyl or methoxymethyl), aralkyl (e.g. benzyl, diphenylmethyl or triphenylmethyl), heterocyclic groups such as tetrahydropyranyl, acyl (e.g. acetyl or benzoyl) and silyl groups such as trialkylsilyl (e.g. t-butyldimethylsilyl). The hydroxyl protecting groups may be removed by conventional techniques. Thus, for example alkyl, silyl, acyl and heterocyclic groups may be removed by solvolysis, e.g. by hydrolysis under acidic or basic conditions. Aralkyl groups such as triphenylmethyl may similarly be removed by solvolysis, e.g. by hydrolysis under acidic conditions. Aralkyl groups such as benzyl may be cleaved by hydrogenolysis in the presence of a Noble metal catalyst such as palladium-on-charcoal. Silyl groups may also conveniently be removed using a source of fluoride ions such as tetra-n-butylammonium fluoride. Carboxyl protecting groups may conveniently be represented by appropriate hydroxyl protecting groups above with deprotection effected according to the methods described above. An example of such a group is an alkyl (e.g. methyl or t- butyl) group which can be removed by acid hydrolysis (e.g. using t fluoroacetic or hydrochloric acid) or an aralkyl (e.g. benzyl) group which can be removed by catalytic hydrogenolysis.

Particularly suitable hydroxyl proteding groups represented by R*³ include acyl groups such as acetyl or benzoyl. An alkylidene protecting group may conveniently be removed by acid-catalysed hydrolysis, for example using thfluoroacetic, sulphuric or hydrochloric acid.

Compounds of formula (I) may also be prepared from other compounds of formula (I) or protected derivatives thereof using conventional interconversion procedures, including N-acylation, N-debenzylation and oxidation of a hydroxyl group to a ketone, followed, if necessary, by the removal of any protecting groups present.

Individual isomers of formula (I) may either be prepared from starting materials having the desired stereochemistry or by epimerisation, resolution or chromatography (e.g. HPLC separation) at an appropriate stage in the synthesis of the required compounds of formula (I) as appropriate using conventional means.

When it is desired to prepare an acid addition salt of a compound of formula (I) the product of the above procedure may be converted into a salt by treatment of the resulting free base with a suitable acid using conventional methods.

Physiologically acceptable acid addition salts of the compounds of formula (I) may be prepared by reacting a compound of formula (I) in the form of a free base with an appropriate acid optionally in the presence of a suitable solvent such as an ester (e.g. ethyl acetate) or an alcohol (e.g. methanol, ethanol or isopropanol).

Inorganic basic salts may be prepared by reacting a compound of formula (I) using conventional methods. Solvates (e.g. hydrates) of a compound of formula (I) may be formed during the work-up procedure of one of the aforementioned process steps.

The following Examples illustrate the invention but do not limit the invention in any way. All temperatures are in ^UC. Hereinafter the term DMSO means dimethylsulphoxide. IMS means industrial methylated spirit.

EXAMPLES

General

Where produds were purified by column chromatography, 'silica' refers to silica gel for chromatography, 0.063 to 0.20mm mesh (e.g. Merck Art 7735); 'flash silica' refers to silica gel for chromatography, 0.040 to 0.063mm mesh (e.g. Merck Art 9385). In this latter case column elution was accelerated by an applied pressure of nitrogen at up to 10 p.s.i

Intermediate 1 1R. 4S. 5R. 6S)-5.6-Dihvdroxy-2-azabicvclor2.2.πheptan-3-one

To a stirred solution of N-methylmorpholine N-oxide (126.7g) in water (390ml) was added a solution of osmium tetroxide (0.5% w/v in f-butanol; 167ml) and a suspension of (1 R, 4S)-2-azabicyclo[2.2.1]hept-5-en-3-one¹ (100g) in f-butanol (500ml). The readion was heated at 70°C for 30 min, then cooled to 50°C. Sodium dithionite was added and the reaction further cooled to 30°C.

Charcoal (Norit Ultra SX+, 40g) was added and stirring continued for 30min. The insolubles were removed by filtration and the filtrate concentrated under vacuum. The residue was refluxed in IMS (1 I) and the inorganic insolubles removed by filtration and the filtrate concentrated to 400ml, heated to reflux then allowed to cool. Filtration afforded the title compound as fawn crystals

(112.7g). m.p. 165.5°C; [aft¹ = -94.9° (c = 1.20, H₂O); ¹H nmr δ (DMSO-d₆) 1.72 (dd, 1 H), 1.90 (dd, 1 H), 2.26 (s, 1H), 3.43 (s, 1 H), 3.74 (m, 2H), 4.99 (dd, 2H), 7.53 (br s, 1 H). 1. SJC Taylor, R McCague, R Wisdom, C Lee, K Dickson, G Ruecroft, F O'Brian, J Littlechild, J Bevan, SM Roberts and TC Evans, Tetrahedron Asymmetry, 1993, 4, 1117.

Intermediate 2

(1 S.2R.6S.7R)-4.4-Dimethyl-3.5-dioxa-8-azatricvclo f5.2.1.0.2.61 decan-9-one

A suspension of (1R, 4S, 5R, 6S)-5-6-dihydroxy-2-azabicyclo [2.2.1] heptan-3- one (10g) in 2,2-dimethoxypropane (200ml) and dimethyl formamide (100ml) was treated with p-toluene sulphonic acid monohydrate (640mg). It was stirred at room temperature for 24h. The reaction mixture was reduced in volume by evaporation in vacuo and the residue was triturated with a small amount of ethyl acetate to give the title compound (5.078g) as a white solid which as collected by filtration.

The mother liquors were evaporated to give a solid residue which was purified by column chromatography on flash silica eluted with methanol-chloroform mixture (0% → 15%) to give more of the title compound (6.696g) as a white solid. H nmr δ (CDCI3) 1.36 (s, 3H), 1.47 (s, 3H), 2.1 (m, 2H), 2.74 (s,1 H), 3.80 (s, 1 H), 4.42 (d, 1H), 4.56 (d, 1 H), 5.99 (s,1 H).

Intermediate 3

(3aR.4S.6R.6aS)-6-Amino-2.2-dimethyl-tetrahvdro-cvclopentaf1.31dioxole-4- carboxylic acid ethylamide (1 S,2R,6S,7R)-4,4-Dimethyl-3,5-dioxa-8-azatricyclo [5.2.1.0. 2,6] decan-9-one

(22.901 g) was treated with neat ethylamine (140ml) in a Hast-C-alloy bomb. It was heated in an oil bath at 159°C for 17h. (The bomb pressure gauge reading was 250 p.s.i) After allowing it to cool down, the pressure was released and the mixture was evaporated to give an oily residue. It was purified by column chromatography on flash silica eluted with methanol chloroform mixture (15% → 50%) to give the title compound (21.34g) as a brown gum. ¹H nmr δ (CDCI3) 1.14 (t, 3H), 1.31 (s, 3H), 1.46 (s, 3H), 1.7-2.5 (m, 2H), 2.77 (m, 1 H), 3.27 (m, 2H), 3.5 (m, 1 H), 4.38 (d, 1H), 4.83 (m, 1 H), 6.60 (s, 1 H). Alternative method for the preparation of Intermediates 2 and 3 A solution of ethylamine (50ml) in dichloromethane (420ml) was stirred under nitrogen and treated dropwise with a solution of trimethyl aluminium (2M) in toluene (85ml). It was stirred at room temperature under nitrogen to give a solution of dimethyl aluminium ethyl amide.

(3aR,4S,6R,6aS)-6-Amino-2,2-dimethyl-tetrahydro-cyclopenta[1 ,3]dioxole-4- carboxylic acid methyl ester hydrochloride (21.21g) as a solid under nitrogen was treated dropwise with the stock solution of dimethylaluminium ethylamide in dichloromethane (260 ml). It was stirred at room temperature under nitrogen for 4hrs and then carefully quenched with water. The mixture was diluted with water (400ml) and extraded with ethyl acetate (1.251 x 2). The organic extract was dried over magnesium sulphate and the solvent was evaporated to give a solid residue (10.121g). This residue was chromatographed on flash silica, eluted with methanol chloroform mixture (10%→ 50%) to give (1 S, 2R, 6S, 7R)-

4-4-dimethyl-3,5,dioxa-8-aza-tricyclo [5.2.1.0. 2,6] decan-9-one as a white solid (6.29g) whose ¹H nmr spectrum (CDCI3) was identical to that of the authentic sample (vide supra) and (3aR,4S,6R,6aS)-6-amino-2,2-dimethyl- tetrahydro-cyclopenta [1,3] dioxole-4-carboxylic acid ethylamide as a gum (4.611g) whose ¹H nmr spectrum (CDCI3) was identical to that of the authentic sample (vide supra).

Intermediate 4

(1 S. 2R. 3S. 4R)-4-Amino-2.3-dihvdroxycvclopentanecarboxylic acid methyl ester, hydrochloride

A solution of (1R, 4S)-2-azabicyclo[2.2.1]hept-5-en-3-one¹ (112.3g) in 3M hydrochloric acid (800ml) was refluxed for 1h. The readion was concentrated under vacuum and the residue evaporated with methanol (800ml) then toluene (3 x 250ml). The resulting solid was dissolved in 1M methanolic HCI (800ml) and refluxed for 1 h. The solvent was removed under vacuum and 2-propanol was added. The resulting slurry was stirred at 0°C for 45min and the title compound isolated by filtration as a light grey solid (147.7g). m.p. 159.8°C; [αβ -14.9° (c = 1.40, ^0); ^ nmr δ (D₂O) 1.86 (m, 1H), 2.54 (m, 1 H), 3.01

(m, 1 H), 3.60 (q, 1 H), 3.77 (s, 3H), 4.10 (t, 1 H), 4.31 (t, 1H). 1. SJC Taylor, R McCague, R Wisdom, C Lee, K Dickson, G Ruecroft, F O'Brian, J Littlechild, J Bevan, SM Roberts and TC Evans, Tetrahedron Asymmetry, 1993, 4, 1117.

Intermediate 5

(3aR.4S.6R,6aS)-6-Amino-2.2-dimethyl-tetrahvdro-cvclopentaM .31dioxole-4- carboxylic acid methyl ester hydrochloride salt

A stirred suspension of (1 S,2R,3S,4R)-4-Amino-2,3-dihydroxy- cyclopentanecarboxylic acid methyl ester hydrochloride (50g, 0.2362 mole), p- toluene sulphonic acid monohydrate (2g) in 2,2-dimethoxypropane (500ml) and

N,N-dimethyl formamide (400ml) was stirred at room temperature for 24h. (It became a clear solution by 2h and again a suspension by 24h). The precipitate was collected by filtration, washed with a small quantity of ethyl acetate to give the title compound (7.95g) as a white solid. The filtrate was evaporated to dryness and the residue was triturated with ethyl acetate to give more of the title compound (47.52o) as a white solid. ¹H nmr δ (D2O) 1.36 (s, 1 H), 1.53 (s,1 H), 2.12 (m, 1 H), 2.61 (m,1 H), 3.20 (m, 1H), 3.76 (m, 1 H), 3.76 (s, 1H), 4.78 (m, 1H), 4.99 (m, 1H).

Intermediate 6

OaR^S.eR.eaS^-e-fδ-Amino^.e-dichloro-pyhmidin-^-ylamino^.Σ-dimethyl- tetrahvdro-cvclopenta [1 ,31 dioxole-4-carboxylic acid ethylamide 5-Amino-2,4,6-trichloropyrimidine (500mg) was treated with a solution of (3aR,4S,6R,6aS)-6-amino-2,2-dimethyl-tetrahydro-cyclopenta [1 ,3]dioxole-4- carboxylic acid ethylamide (581 mg) in butan-1-ol (26 ml) and triethylamine

(3.5ml). The reaction mixture was heated under reflux under nitrogen for 22h. It was allowed to cool and the solvent was removed under reduced pressure to give a residue (1.886g). This residue was purified by column chromatography on flash silica, eluted with ethyl acetate-cyclohexane mixtures (33% → 75%) to give the title compound as a foam (742mg) MH+ measured at 390.109909 C-j 5

H22 CI2 N5 O3 requires 390.109970, ¹H nmr δ (CDCI3) 1.18 (t, 3H), 1.28 (s, 1H). 1.46 (s, 1 H), 1.85-2.67 (m,2H) 2.85 (d, 1 H), 3.32 (m,2 H), 3.66 (s, 2H), 4.52 (d, 1H), 4.75 (t, 2H), 5.94 (s, 1 H), 8.06 (d 1 H).

Intermediate 7 (3aR,4S.6R.6aS,-6-(2.6-Dichloro-5-methoxymethyleneamino-pyrimidin-4- ylamino)-2.2-dimethyl-tetrahvdro-cvclopenta f 1.31 dioxole-4-carboxylic acid ethylamide

Trimethyl orthoformate (4ml) and concentrated hydrochloric acid (0.05ml) were added to (3aR, 4S, 6R, 6aS)-6-(5-Amino-2,6-dichloro-pyrimidin-4-ylamino)-2,2- dimethyl-tetrahydro-cyclopenta [1,3] dioxole-4-carboxylic acid ethylamide (250mg). The reaction mixture was stirred at room temperature for 2h and then the solvent removed under reduced pressure to give a gum (352 mg). It was purified on flash silica, eluted with ethyl acetate-cyclohexane mixtures (20% - 50%) to give the title compound as a white foam (161mg_p). MH⁺ measured at

432.120908 C17 H24 CI2 N5 O4 requires 432.120535; ¹H nmr δ (CDCI3) 1.15 (t, 3H), 1.27 (s, 3H), 1.47 (s, 3H), 1.80 - 2.60 (m, 2H), 2.80 (d, 1H), 3.26 (m, 2H), 4.11 (s, 3H), 4.49 (d, 1 H), 4.75 (m, 2H), 5.79 (s, 1 H), 7.86 (s, 1 H), 8.09 (d, 1H).

Intermediate 8

(3aR.4S.6R.6aS)-6-(2.6-Dichloro-pu n-9-vn-2.2-dimethyl-tetrahvdro- cvclopentaH .31 dioxole-4-carboxylic acid ethylamide

A stirred solution of (3aR,4S,6R,6aS)-6-(2,6-Dichloro-5- methoxymethyleneamino-pyrimidin-4-ylamino)-2,2-dimethyl-tetrahydro- cyclopenta[1,3]dioxole-4-carboxylic acid ethylamide (560mg) in butan-1-ol (15ml) was heated under reflux for 4h. It was allowed to cool and the solvent was evaporated under reduced pressure to give an oily residue (637mg). This residue was purified by column chromatography on flash silica, eluted first with ethyl acetate-cyclohexane mixtures (25% - 83%) then with 10% methanol in chloroform to give the title compound as a gum (46mg). MH⁺ measured at 400.09422 C₁₆ H₂o CI2 N5 O3 requires 400.094320; ¹H nmr δ (CDCI3) 1.18 (t, 3H), 1.23 (s, 3H), 1.59 (s 3H) 2.68 (m, 2H), 2.86 (m, 1H), 3.35 (m, 2H), 4.96 (m. 3H) 5.77 (t, 1 H), 8.32 (s, 1 H).

Alternative Preparation of Intermediate 8.

Triethylorthoformate (8ml) and concentrated hydrochloric acid (0.1ml) was added to (3aR,4S,6R,6aS)--6-(5-Amino-2_I6-dichloro-pyrimidin-4-ylamino)-2,2- dimethyl-tetrahydro-cyclopenta [1 ,3] dioxole-4-carboxylic acid ethylamide (500 mg). The reaction mixture was stirred at room temperature for 24h and then the solvent was evaporated under reduced pressure to give a gum. This gum was treated with butan-l-ol (15ml) and heated under reflux under nitrogen for 4 days. It was allowed to cool and the solvent was evaporated under reduced pressure to give a brown foam (576mg). This was purified by column chromatography on flash silica eluted with methanol-chloroform mixtures (0%

→ 5%) to give (3aR. 4S.6R. 6aS)-6-(2.6-Dichloro-purin-9-yl -2.2-dimethyl- tetrahvdro-cvclopenta M .31 dioxole -4-carboxylic acid ethylamide as a gum (87mg) which was identified on t.l.c. to the authentic material described above, and a more polar product (1 S.2R.3S.4R)-4-(2.6-Dichloro-purin-9-vD-2.3- dihvdroxy-cvclopentanecarboxylic acid ethylamide (Intermediate 11 ) as a gum

(122mg).

Intermediate 9 (3aR.4S.6R.6aS)-6-r2-Chloro-6-(2.2-diphenyl-ethylamino)-purin-9-vn-2.2- dimethyl-tetrahvdro-cyclopentaf 1.31dioxole-4-carboxylic acid ethylamide

(3aR,4S,6R,6aS)-6-(5-Amino-2,6-dichloro-pyrimidin-4-yl-amino)-2,2-dimethyl- tetrahydro-cyclopenta[1,3]dioxole-4-carboxylic acid ethylamide (12.21 g) in diethoxymethyl acetate (240ml) was heated at reflux, under nitrogen, for 2 days. A futher addition of diethoxymethyl acetate (75ml) was made and the heating was continued for a further 24h. The solvent was evaporated under reduced pressure to give a brown gum (17.62g) which was chromatographed on flash silica eluting with ethyl acetate-cyclohexane mixtures (1:4→4:1 ). Appropriate fractions were combined and evaporated to give a gum (3.382g). A portion (100mg) of this material, 2,2-diphenylethylamine (62mg) and N,N- diisopropylethylamine (40.5mg) were heated under reflux in isopropanol (7ml) for 18h. The solution was cooled to room temperature, poured into water and extracted with ethyl acetate (2x50ml). The organic extracts were combined, washed with water (50ml), dried (MgSO_ι) and evaporated under reduced pressure to give a brown gum (150mg). This was chromatographed on flash silica eluting with ethyl acetate-cyclohexane mixtures (1 :1-1 :0). Fractions which contained the major component were combined and evaporated to give the title compound as a cream coloured solid (66mg). MH⁺ =561 ; i.r. (CHBr3) v includes 3420.6, 1616.5cm^{"1 '}> ¹H nmr δ (CDCI3) includes 1.18 (t, 3H), 1.31 (s, 3H), 1.56 (s, 3H), 2.45-2.71 (m, 2H), 2.74-2.87 (m, 1 H), 3.24-3.41 (m, 2H), 4.25 (bs, fine coupling, 2H), 4.36 (t, 1H), 4.78-5.0 (m, 3H), 5.78 (s, fine coupling, 1 H), 5.94 (s, 1H), 7.08-7.41 (m, 10H), 7.77 (s, 1H).

Alternative Preparations of Intermediate 9: 1. (3aR, 4S, 6R, 6aS)-6-(2,6-Dichloro-puhn-9-yl)-2,2-dimethyl-tetrahydro- cyclopenta [1 ,3] dioxole-4-carboxylic acid ethylamide (85mg) was treated with 2,2-diphenylethylamine (959 mg), N,N-disopropylethylamine (0.053 ml) and propan-2-ol (2.8 ml). The reaction mixture was heated under reflux under nitrogen for 18h. More 2,2-diphenylethylamine (29 mg), N,N- disopropylethylamine (0.026 ml) were added and the reation mixture heated under reflux for a further 10h. The reaction mixture was allowed to cool and the solvent was evaporated under reduced pressure to give a brown foam (174 mg). This foam was purified by column chromatography on flash silica, eluted with methanol-chloroform (0% → 3%) to give the title compound (86mg) whose ¹ H nmr spectrum (CDCI3) was identical to that of the authentic sample.

2. (3aR,4S,6R,6aS)-6-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yl]-2,2- dimethyl-tetrahydro-cyclopenta[1 ,3]dioxole-4-carboxylic acid (1 g) was dissolved in dry DMF (10 ml) and treated with triethylamine (0.28 ml). The solution was then cooled to 0 °C while pivaloyl chloride (0.3 ml) was added dropwise with stirring. After the addition was complete the mixture was stirred a further 45 min. at 0 °C. A solution of ethylamine (1 ml) in DMF (4 ml) was then added and the mixture allowed to warm to 21 °C. After 24 h the mixture was diluted with ethyl acetate (150 ml) and washed with 2N HCI (100 ml) followed by saturated sodium hydrogen carbonate solution and finally brine (each 100 ml) The organic layer was dried (MgSθ4) and evaporated under reduced pressure. The crude product was then purified by flash silica chromatography (eluant 5% methanol in chloroform) to give the title compound as a foam (670 mg) found to be identical to authentic material by ¹ H nmr.

Intermediate 10

(1S.2R.3S.4R -4-f2-Chloro-6-(2.2-diphenyl-ethylamino)-purin-9-yl1-2.3- dihvdroxy-cvclopentanecarboxylic acid ethylamide (3aR,4S,6R,6aS)-6-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yl]-2,2- dimethyl-tetrahydro-cyclopenta[1 ,3]-dioxole-4-carboxylic acid ethylamide (300mg) was stirred in thfluoroacetic acid (3.6ml) and water (0.4ml) at room temperature for VΛh. The solution was evaporated under reduced pressure and the residue was evaporated several times from ether to give a cream coloured foam (258mg). This was purified by reverse phase HPLC (30-70% acetonitrile) to give the title compound as a solid (86mg). MH⁺=, 521; ¹H nmr δ (CD3OD) includes 1.14 (t, 3H), 2.07-2.23 (m, 1 H), 2.49-2.64 (m, 1 H), 2.79- 2.91 (m, 1 H), 3.24 (q, 2H), 4.16-4.26 (m, 3H), 4.35-4.52 (m, 3H), 7.12-7.36 (m, 10H), 8.24 (s, 1 H).

Alternative Preparations of Intermediate 10

1. A solution of (3aR,4S,6R,6aS)-6-[2-Chloro-6-(2,2-diphenyl-ethylamino)- purin-9-yl]-2,2-dimethyl-tetrahydro-cyclopenta [1,3] dioxole-4-carboxylic acid ethylamide (250 mg) in acetonitrile (7ml) was treated with 2M hydrochloric acid (12.5ml) The readion mixture was stirred at room temperature for 1.75h. The solvent was evaporated under reduced pressure and then azeotroped with toluene to give a gum (312mg). This was purified by column chromatography on flash silica, eluted with dichloromethane: methanol: 0.88 aqueous ammonia (30:4:1 ) to give the title compound as a white foam (226mg) ¹H nmr consistent with authentic sample.

2. (1S, 2R, 3S, 4R)-4-(2-6-Dichloro-purin-9-yl)-2,3-dihydroxy-cyclopentane carboxylic acid ethylamide (144 mg) was treated with 2,2-diphenyl ethylamine (110mg), N.N-disopropyl ethylamine (0.098 ml) and propan-2-ol (6ml). The reaction mixture was heated under reflux under nitrogen for 17h. The readion mixture was allowed to cool and the solvent was evaporated under reduced pressure to give a white foam (285 mg) which was purified by column chromatography on flash silica, eluted with dichloromethane: methanol: 0.88 aqueous ammonia (30:4:1 ) and crystallized from methanol to give the title compound as a white solid (149 mg). Its ¹ H nmr spedrum (CD3OD) was identical to that of the authentic sample.

Intermediate 11

M S. 2R. 3S. 4R)-4-r2.6-Dichloro-puhn-9-vn-2.3-dihvdroxy- cvclopentanecarboxylic acid ethylamide Trimethyl orthoformate (8ml) and concentrated hydrochloric acid (0.1ml) was added to (3aR, 4S, 6R, 6aS)-6-(5-Amino-2,6-dichloro-pyrimidin-4-ylamino)-2,2- dimethyl-tetrahydro-cyclopenta [1 ,3] dioxole-4-carboxylic acid ethylamide (500 mg). The readion mixture was stirred at room temperature for 4.5h and then the solvent was removed under reduced pressure to give a brown foam. The foam was treated with butan-1-ol (15ml) and heated under reflux under nitrogen for 18h. The readion mixture was allowed to cool and the solvent was evaporated under reduced pressure to give a gum. A solution of the gum in acetonitrile (25ml) was treated with 2M hydrochloric acid (40ml) and stirred at room temperature for 3h. The solvent was removed under reduced pressure by azeotroping with toluene several times to give a gum (489 mg). This gum was purified by column chromatography on flash silica, eluted with methanol- chloroform (2% → 10%) to give the title compound as a white foam (160 mg). MH⁺ measured at 360.062820 C13 H-je CI2 N5 O3 requires 360.063020; ¹H nmr δ (CD3OD) 1.15 (t, 3H), 2.27 (m, 1 H), 2.65 (m, 1 H), 2.88 (m, 1H), 3.26 (q,

2H), 4.26 (t, 1H), 4.51 (m, 1H), 4.98 (m, 1 H), 8.84 (s, 1 H).

Intermediate 12 (1 S.2R.3R.5R)-2-Acetoxy-3-acetoxymethyl-5-(2-amino-6-oxo-1.6-dihvdro- purin-9-v0-cvclopent-1 -yl acetate

Carbocyclic Guanosine² (38g) was dissolved in acetonitrile (760 ml). Dimethylaminopyridine (200 mg) was then added and the solution maintained at 20 °C in a water bath. Acetic anhydride (47.5 ml) was then added dropwise over 35 min. with stirring. After 1 h the dark solution was treated with methanol (40 ml) and stirred for a further 20 min. Evaporation of the solvent under reduced pressure gave the crude product as an oil. Trituration of this oil with water (200 ml) gave the title compound as a brown solid (41 g). MH⁺ measured at 408.151909 C17H22N5O7 requires 408.151923. ^"- H nmr δ (DMSO-d6) includes 7.86 (s, 1H), 6.46 (s, 2H), 5.57 (m, 1 H), 5.21 (m, 1 H), 4.85 (m, 1 H), 4.20 (m, 2H), 3.4 (m, 1 H), 2.35 (m, 1 H), 1.85 (m, 1 H), 2.1 (s, 3H), 2.08 (s, 3H),

1.95 (s, 3H). ²A.M. Exall et al, J. Chem. Soc, Perkin Trans. I, 1991 , 2467.

Intermediate 13 (1S.2R.3R.5R)-2-Acetoxy-3-acetoxymethyl-5-(2-amino-6-chloro-purin-9-vn- cvclopent-1-yl acetate

(1S,2R,3R,5R)-2-Acetoxy-3-acetoxymethyl-5-(2-amino-6-oxo-1 ,6-dihydro- purin-9-yl)-cyclopent-1-yl acetate (10g) was suspended in dry acetonitrile (50 ml) and treated with tetraethylammonium chloride (8.15g) giving a clear solution. To this was added N.N-dimethylaniline (3.15 ml). The resulting mixture was stirred while phosphorus oxychloride (13.6 ml) was added dropwise over 15 min. The mixture was then heated to reflux for 10 min. After cooling the solvent was then removed under reduced pressure. The residue was then dissolved in chloroform (200 ml) and washed with cold water (2 x 150 ml). The organic layer was dried (MgS04) and evaporated under reduced pressure to give a gum. This was purified on flash silica eluting with ethyl acetate to give the title compound as a white foam. (6.64g). MH⁺ Measured at 426.116532 C17H21CIN5O6 requires 426.118036. ^H nmr δ (DMS-d6) includes 8.33 (s, 1 H), 6.95 (bs, 2H), 5.59 (dd J 8.5 Hz, 6.0 Hz, 1 H), 5.21 (dd J

6.0 Hz, 4.0 Hz, 1H), 4.93 (m, 1 H), 4.25 ( dd J 11.0 Hz, 6.5 Hz, 1H), 4.15 (dd J 11 Hz, 5.5 Hz, 1 H), 2.5 (m, 1 H), 2.39 (m, 1 H), 2.00 (s, 3H), 2.10 (s, 3H), 1.98 (m, 1 H), 1.95 (s, 3H).

Intermediate 14

(1S.2R.3R.5R)-2-Acetoxy-3-acetoxymethyl-5-(2.6-dichloro-purin-9-vh- cvclopent-1-yl acetate

(1S,2R,3R,5R)-2-Acetoxy-3-acetoxymethyl-5-(2-amino-6-chloro-purin-9-yl)- cyclopent-1 -yl acetate (77.23g) was dissolved in dry dichloromethane (2.5 I) and treated with pyridine hydrochloride (42.5g), followed by cupric chloride

(1.8g). The resulting green solution was cooled to -15 ^CC under nitrogen. Tert- butyl nitrite (105ml) was then added dropwise with stirring over 30 min. After the addition was complete the mixture was allowed to warm to 21 ^CC overnight. After 24 h the mixture was washed with cold water (2 x 200 ml) dried (MgSθ4) and treated with a mixture of decolourizing charcoal (5g) and flash silica (25g).

Filtration and evaporation under reduced pressure then gave an oil. Trituration with 2-propanol gave the title compound as a buff solid (33.5g). Concentration of the mother liquors gave a second crop (31.1g). MH⁺ measured at 445.068132 C17H19CI2N4O6 requires 445.068165; ^"Η nmr δ (DMSO-d6) includes 8.92 (s, 1H), 5.61 (m, 1H), 5.25 (m, 1H), 5.12 (m, 1H), 4.35 - 4.1 (m, 2H), 2.70 - 2.30 (m, 2H), 2.1 (m, 1 H), 2.08 (s, 3H), 2.06 (s, 3H), 1.92 (s, 3H).

Intermediate 15 (1 S.2R.3R.5R)-2-Acetoxy-3-acetoxymethyl-5-r2-chloro-6-(2.2-diphenyl- ethylamino)-purin-9-yll-cvclopent-1 -yl acetate (1 S,2R,3R,5R)-2-Acetoxy-3-acetoxymethyl-5-(2,6-dichloro-purin-9-yl)- cyclopent-1-yl acetate (3.0 g) was dissolved in dry 2-propanol (100 ml) and treated with diphenylethylamine (1.7 g), followed by N,N-diisopropylethylamine (1.77 ml). The resulting mixture was heated to reflux under nitrogen. After 4 h the solvent was removed under reduced pressure and the resultant oil purified on flash silica eluted with ethyl acetate, to give the title compound as a buff foam (2.64g). MH⁺ measured at 606.211823 C31 H32CIN5O6 requires 606.211937. ¹ H nmr δ (DMSO-d6) includes 8.34 ( m, 1H), 8.27 (s, 1H), 7.4 - 7.1 (m, 10H), 5.56 (m, 1 H), 5.23 (m, 1 H), 4.96 (m, 1H), 4.55 (m, 1 H), 4.3 - 3.99

(m, 4H), 2.4 (m, 1H), 2.08 (s, 3H), 2.0 (m, 1H), 2.02 (s, 3H), 1.93 (s, 3H).

Intermediate 16 (1 R.2S.3R.5R)-3-r2-chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yll-5- hvdroxymethyl-cvclopentane-1.2-diol

(1S,2R,3R,5R)-2-Acetoxy-3-acetoxymethyl-5-[2-chloro-6-(2,2-diphenyl- ethylamino)-purin-9-yl]-cyclopent-1-yl acetate (900 mg) was dissolved in dry methanol (20 ml) and treated with a solution of 30% sodium methoxide in methanol (30 μl). The resulting mixture was stirred at 21 °C under nitrogen for 1 h. Dowex 50xW acid resin was then added until the mixture was neutral to wet pH paper. Filtration and evaporation under reduced pressure then gave the title compound as a foam (561 mg). MH⁺ measured at 480.179916 C25H27CIN5O3 requires 480.180243. ¹ H nmr δ (DMSO-d6) includes 8.18 (s, 1H), 7.4-7.16 (m, 10H), 4.63 (m, 1 H), 4.57 (m, 1 H), 4.25 (m, 1 H), 4.04 (m, 1 H), 3.83 (m, 1 H), 3.52 - 3.4 (m, 2H), 2.23 (m, 1 H), 2.03 (m, 1 H), 1.61 (m, 1 H).

Intermediate 17

(3aR.4R.6R.6aS⁾-f6-r2-Chloro-6-⁽2.2-diphenyl-ethylamino⁾-^purin-9-yll-2.2- dimethyl-tetrahvdro-cvclopentaf1.3ldioxol-4-vn-methanol (1 R.2S,3R,5R)-3-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yl]-5- hydroxymethyl-cyclopentane-1 ,2-diol (2g) was dissolved in acetone (40 ml) containing para-toluenesulfonic acid (1.7g). 2,2-Dimethoxypropane (7.5 ml) was then added and the resulting mixture stirred at 21 °C for 3 h. The solvent was then removed under reduced pressure and the residue dissolved in ethyl acetate (250 ml). This was washed successively with aqueous sodium hydrogen carbonate (100 ml) and brine (100 ml). The organic layer was then dried (MgSθ4) and evaporated to give the title compound as a foam (2.1g). MH⁺ measured at 520.211472 C28H31CIN5O3 requires 520.211543. ¹H nmr δ (DMSO-d6) includes 8.40 (s, 1 H), 8.30 (s, 1 H), 7.40 - 7.14 (m, 10H), 5.00 -

4.46 (m, 5H), 4.07 (m, 3H), 3.51 (m, 2H), 2.38 - 2.01 (m, 3H), 1.50 (s, 3H), 1.25 (s, 3H).

Intermediate 18 OaR^S.eR.eaS^^-Chloro-e-^^-diphenyl-ethylamino purin-g-vn^^- dimethyl-tetrahvdro-cyclopentaH .31dioxole-4-carboxylic acid (3aR,4R,6R,6aS)-[6-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yl]-2,2- dimethyl-tetrahydro-cyclopenta[1,3]dioxol-4-yl]-methanol (1.85g) was dissolved in a mixture acetonitrile, carbon tetrachloride, and water (each 19 ml). Sodium periodate (3.4 g) was added and the mixture cooled to 5 °C in a cold water bath. Ruthenium trichloride trihydrate (93.6 mg) was then added and the mixture stirred at 5 °C for 1 h. The readion mixture was then diluted with ethyl acetate (200 ml) and washed with aqueous sodium bisulfite (100 ml), followed by brine (100 ml). The organic layer was dried (MgSO4) and evaporated under reduced pressure to give the title compound as a dark foam (1.9 g). MH⁺ measured at 534.190216 C28H29CIN5O4 requires 534.190807. ¹ H nmr δ (CD3OD) includes 8.03 (s, 1 H), 7.36 - 7.12 (m, 10H), 5.10 (m, 2H), 4.95 - 4.70 (m. 1 H), 4.47 (t, J 7.5Hz, 1 H), 4.20 (m, 2H), 3.05 (m, 1H), 2.60 (m, 2H), 1.56 (s, 3H). 1.32 (s, 3H).

Example 1

(1S.2R.3S.4R)-4-rtrans-2-(4-Amino-cvclohexylamino)-6-(2.2-diphenyl- ethylamino)-purin-9-yl1-2.3-dihydroχy-cyclopentanecarboxylic acid ethylamide (3aR,4S,6R,6aS)-6-[2-Chloro-6-(2,2-diphenyl-ethylamino)-ρurin-9-yl]-2,2- dimethyl-tetrahydro-cyclopenta[1 ,3]dioxole-4-carboxylic acid ethylamide (Intermediate 9, 500mg) and trans-1 ,4-diaminocyclohexane (1.018g) were stirred under nitrogen in anhydrous dimethylsulphoxide (15ml) at 130°C for 24h and the solution was then stood at room temperature for 72h. The mixture was poured into aqueous sodium chloride solution (300ml) and partitioned with ethyl acetate (2x150ml). The organic extracts were combined, dried (MgS0 ) and evaporated under reduced pressure to give a yellow/brown foam (569mg). This was chromatographed on flash silica eluting with dichloromethane:methanol:880 ammonia solution (30:4:1 ). Fradions which contained a mixture of a less polar and more polar component were combined and evaporated to give a yellow solid (344mg). This was dissolved in trifluoracetic acid (4.5ml) and water (0.5ml) and stirred at room temperature for 2h. The solvent was evaporated and the residue was evaporated several times from ether to give a yellow/brown foam (617mg). This was purified by column chromatography on flash silica eluting with dichloromethane:methanol:880 ammonia solution (30:6:1 ).

Fradions which contained the major component were combined and evaporated to give the title compound as a pale yellow amorphous solid (145mg), M/Z 599 (MH⁺), ¹H nmr (DMSO-d₆) δ includes 1.03 (t, 3H), 1.25 (m, 5H), 1.71-2.01 (m, 6H), 2.19-2.36 (m, 1 H), 2.58-2.74 (m, 2H), 3.10 (m, 2H),

4.06 (m, 2H), 4.23 (m, 1H), 4.43-4.64 (m, 2H), 6.12 (broad, 1H), 7.12-7.39 (m, 10H), 7.78 (s, 1H), 7.92 (t, 1H).

Example 2 Alternative preparation of:

(1 S.2R.3S.4R)-4-ftrans-2-(4-Amino-cvclohexylamino-6-(2.2-diphenyl- ethylamino-purin-9-vn-2.3-dihvdroxy-cvclopentanecarboxylic acid ethylamide A solution of (1 S,2R,3S,4R)-4-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9- yl]-2,3-dihydroxy-cyclopentanecarboxylic acid ethylamide (Intermediate 10, 775 mg) in dry dimethyl sulphoxide (23 ml) was treated with 1,4-trans- diaminocyclohexane (1.905g). The reaction mixture was heated under reflux under nitrogen for 5 days. It was allowed to cool and then treated with saturated sodium chloride solution (115ml). This was extraded with ethyl acetate (280ml x 4), dried over magnesium sulphate and the solvent was evaporated under reduced pressure to give an oily residue (2.3g). It was purified by column chromatography on flash silica eluted with dichloromethane: methanol: 0.88 aqueous ammonia (30:6:1 ) to give the title compound as a brown foam (334 mg) MH⁺ measured at 599.345505 C33 H43 NQ O3 requires 599.345813; ¹H nmr δ (DMSO-d₆) was identical to that of the authentic sample.

Example 3

(1S.2R.3S.4R)-4-r6-(2.2-Diphenyl-ethylamino -2-f2-(piperidin-1-yl)-ethylamino1- purin-9-yl1-2.3-dihvdroxy-cvclopentane carboxylic acid ethylamide (1S,2R,3S,4R)-4-[2-Chloro-6-(2,2-diphenyl-ethylamino)-purin-9-yl]-2,3- dihydroxy-cyclopentanecarboxylic acid ethylamide (Intermediate 10, 400 mg) was dissolved in dry dimethylsulfoxide (5 ml). 1-(2-Aminoethyl)-pipehdine (1.1 ml) was added and the mixture heated to 126 °C under nitrogen, for 24 h. The cold readion mixture was diluted with ethyl acetate (150 ml) and extraded with 5% citric acid solution (100ml). This was washed with ethyl acetate (50 ml) then basified with 10% sodium hydroxide solution to pH 8. The aqueous layer was extracted with ethyl acetate (2 x 100 ml) and the combined extracts dried (MgSO4), and evaporated under reduced pressure to give the title compound as a foam (350 mg). ¹H nmr δ (CDCI3) includes 7.43 (s, 1H), 7.36 (m, 10H), 4.55 - 4.1 (m, 6H), 3.55 - 3.25 (m, 4H), 2.85 (m, 1 H), 2.77 - 2.32 (m, 8H), 1.66 - 1.36 (m, 6H), 1.18 (t, 7 Hz, 3H).

Example 4

(1 S.2R.3S.4R)-4-r6-(2.2-Diphenyl-ethylamino)-2-r2-(1 -methyl-1 H-imidazol-4- vπ-ethylaminol-purin-9-yll-2.3-dihvdroxy-cyclopentanecarboxylic acid ethylamide

A suspension of 1 -methyl histamine (198mg) dihydrochloride in dry methanol was treated with a solution of sodium hydroxide in dry methanol (1.7ml of a 25ml solution containing 1.1g NaOH). After stirring at 21 °C for 15min. the solvent was removed under reduced pressure and the residue dissolved in dimethylsulphoxide (2ml). To this was then added (1S,2R,3S,4R)-4-[2-Chloro-

6-(2,2-diphenyl-ethylamino)-purin-9-yl]-2,3-dihydroxy-cyclo-pentanecarboxylic acid ethylamide (Intermediate 10, 120mg) and the resulting mixture heated to 130°C under nitrogen. After 48h the mixture was allowed to cool and diluted with ethyl acetate (100ml). This was washed with brine (3x 25ml) and the combined aqueous layers back-extracted with ethyl acetate (25ml). The combined extracts were dried and evaporated to give a black tar. This was purified by preparative thin layer TLC (dichloromethane, ethanol, 880- ammonia, 100/8/1 ) to give the title compound (46mg) as a foam. MH⁺ = 610, 1 H nmr δ (CD3OD) includes 7.80 (s,1 H), 7.48(s, 1H), 7.35-7.14 (m, 10H), 6.76 (s, 1 H), 4.66(m, 1H), 4.55-4.30 (m, 4H), 4.18 (m, 3H), 3.64 (s, 3H), 3.23 (q,

2H), 2.82(11., 3H), 2.50 (m, 1H), 2.22 (m,1H), 1.14 (t, 3H).

The effects of compounds of the invention on fMLP activation of O2^* generation The potential for compounds of formula (I) to inhibit leukocyte fundion was examined by measuring the ability of the compounds to inhibit superoxide (O2^') generation from neutrophils stimulated with fMLP following the procedure described by W. Busse et al. in J. Allergy Clin. Immunology, 83(2) Part 1 , 400- 405 (1989). Thus, compounds of Examples 1 to 4 were at least four fold more active than NECA in this study. Indeed, the compound of Example 4 is 50 times more potent than NECA in this study.

Claims

1. A compound of formula (I)

HO OH and salts and solvates thereof, wherein:

R¹ represents a hydrogen atom or a C3_8cycloalkyl or

group; R2 represents a group selected from (0 C3_8cycloalkyl (ii) C3_8cycloalkyl substituted by one or more groups (e.g. 1 , 2 or 3 groups) which may be the same or different and are selected from C2-7acylamino, guanidino, carboxyl, oxo and (CH2)pR³ (where p is zero or 1 and R³ is hydroxy, NH2, C-|_6alkylamino or diC-|^alkylamino) (iii) pyrrol idin-3-y I, 2-oxopyrrolidin-4-yl, 2-oxopyrrolidin-5-yl, piperidin-3-yl or piperidin-4-yl in which the ring nitrogen atom is substituted by hydrogen,

C-_j-galkyl or arylC-ι_galkyl (e.g. benzyl) (iv) pyrrolidin-3-yl, piperidin-3-yl or piperidin-4-yl in which the ring nitrogen atom is substituted by hydrogen, Cι_galkyl or arylC-j^alkyl (e.g. benzyl) and one or more of the ring carbon atoms (e.g. 1 , 2 or 3 ring carbon atoms) is substituted by the same or different groups selected from

C2_7acylamino, guanidino, oxo and (CH2)pR³ (where p and R³ are as defined previously) (v) C3_8cycloalkylC-i_6alkyl

(vi) C3_8cycloalkylC-|-6alkyl in which one or more of the ring carbon atoms (e.g. 1 , 2 or 3 ring carbon atoms) is substituted by the same or different groups seleded from C2-7acylamino, guanidino, carboxyl, oxo and (CH2)pR (where p and R³ are as defined previously) (vii) -Alk-jY where Alk** is a C2-6 alkylene group and Y is a group selected from C2-7acylamino, guanidino, hydroxyl, NH2, C-|_6alkylamino, diCι_6alkylamino or

(where X is a bond, 0, CH2 or NR⁴ in which R⁴ is hydrogen, C^alk l or arylC-|_6alkyl) and (viii) -(CHR*5)_m(Alk2)nZ where m and n each independently represent zero or 1 except that when m is 1 then n must also represent 1 , R5 is a hydrogen atom or a carboxy group or a group CH2R (where R6 is C2-7acylamino, guanidino, hydroxy, methoxy, NH2,

Alk2 is a C-]_5alkylidene group and Z is a hydrogen atom or an optionally substituted aromatic ring selected from phenyl, pyridyl, pyrimidinyl, imidazolyl, triazolyl, tetrazolyl and benzimidazolyl where the ring is optionally substituted by one or more groups (e.g. 1 , 2 or 3 groups) which may be the same or different and are seleded from C*j_6alkyl,

C2-7acylamino, guanidino, carboxyCι-»alkyl, hydroxy, NH2, C*j_ βalkylamino or diC*ι_6alkylamino; Q represents an oxygen or sulphur atom; and Ph represents phenyl.

2. A compound according to Claim 1 in which R¹ is C*ι_3 alkyl.

3. A compound according to Claim 1 or Claim 2 in which Q is an oxygen atom.

4. A compound according to Claim 1 in which R¹ NHC(=Q)- is ethylami nocarbonyl .

5. A compound according to any preceding claim in which R2 is cyclopentyl or cyclohexyl each substituted by one or two groups seleded from hydroxy, NH2, methylamino, dimethylamino, acetamido or trifluoroacetamido.

6. A compound according to any of Claims 1 to 4 in which R² is pyrrolidin-3- yl or piperidin-3-yl in which the respective rings may each be substituted by hydrogen, C*j_3 alkyl or benzyl.

7. A compound according to any of Claims 1 to 4 in which R2 is -(CHR⁵)m(Alk2)_nZ in which Z is an optionally substituted imidazolyl group.

8. A compound according to Claim 7 in which -(CHR^)m(Alk2)_n- is -CH₂CH₂-.

9. A compound according to any of Claims 1 to 4 in which R² is Alk*ιY where Alk*ι is a C2 alkylene group and Y is

-N X

(where X is a bond, O, CH2).

10. (1 S_I2R,3S,4R)-4-[trans-2-(4-Amino-cyclohexylamino)-6-(2,2-diphenyl- ethylamino)-purin-9-yl]-2,3-dihydroxy-cyclopentanecarboxylic acid ethylamide;

(IS^R^S^RH-ie^^-Diphenyl-ethylamino^-p^piperidin-l-yl)- ethylamino]-purin-9-yl]-2,3-dihydroxy-cyclopentane carboxylic acid ethylamide;

(1 S,2R,3S,4R)-4-[6-(2,2-Diphenyl-ethylamino)-2-[2-(1 -methyl-1 H- imidazol-4-yl)-ethylamino]-purin-9-yl]-2,3-dihydroxy- cyclopentanecarboxylic acid ethylamide; and physiologically acceptable salts and solvates thereof.

11. A compound of formula (I) as defined in any preceding claim for use in human or veterinary medicine.

12. Use of a compound of formula (I) as defined in any of Claims 1 to 10 for the manufacture of a medicament for the treatment of patients with inflammatory conditions who are susceptible to leukocyte-induced tissue damage.

13. A pharmaceutical composition comprising a compound of formula (I) as defined in any of Claims 1 to 10 together, if desirable, with one or more physiologically acceptable carriers or excipients.

14. A process for the preparation of a compound of formula (I) as defined in claim 1 which comprises; (A) treating a compound of formula (II)

OR^* OR^b

(wherein R^a and R^b each represent a hydrogen atom or together form an alkylidene group such as isopropylidene) with an amine R^NH-* (wherein R^2a is a group R² or a protected derivative thereof), followed, where necessary, by the removal of any protecting groups present; or

(B) deprotecting a protected derivative of a compound of formula (I), if necessary or desirable followed by (I) salt formation or (II) conversion of a compound of formula (I) to a different compound of formula (I) or (III) preparation of an individual isomer of a compound of formula (I).

15. A method for the treatment of a human or animal subject with an inflammatory condition which is susceptible to leukocyte-induced tissue damage, which method comprises administering to said subject an effedive amount of a compound of formula (I) or a physiologically acceptable salt or solvate thereof.

16. Compounds according to any of Claims 1 to 10 substantially as herein described.

17. Compositions according to Claim 13 substantially as herein described.

18. A process for the preparation of a compound according to Claim 1, the process substantially as herein described and exemplified.