SI8910123A - Dideoxy-dihydro-carbocyclic nucleosides - Google Patents

Abstract

A process for the preparation of compounds of formula is described / ♦ \ I Ϋ'ϊ λλ I N Y HOCH, ΛΧ N \ ___ / t wherein X is H, NRR1, SR, OR, or halogen; Zje H OR2 or NRR1; R, R1, R2 are H, C1-4alkyl or aryl and their pharmaceutically acceptable derivatives. Right this describes the use of compounds prepared according to the process of the invention as antiviral and antitumor agents, and pharmaceutical formulations that contain.

Description

REGENTS OF THE UNIVERSITY OF MINNESOTA, USA

DIDEOXIDEHYDROCARBOCYCLIC NUCLEOSIDES

The present invention is directed to dideoxycarbocyclic nucleoside analogues. The closer the relations carbocyclic 2 ', 3'-dideoxy-2 ^1, 3'-didehydro purine nucleoside analogues and njihovu upotrebu in therapy, in particular as a antivirusnog means.

In terms of similarity between the functions of the virus cell and the host cell, it is difficult to selectively attack the virus without leaving the host cell intact. Thus, there are a relatively small number of agents that are effective against the virus per se and it is difficult to find antiviral agents that have an acceptable therapeutic index, ie. agents that have a significant antiviral effect at the dose limit at which the agent has acceptable toxicity or an adverse event.

One group of viruses that has recently been given the highest importance is the retroviruses responsible for Acquired Immune Deficiency Syndrome (AIDS). Such viruses have been previously referred to under various names, but are now known by the general name of Human Immunodeficiency Virus (HIV); two such viruses, HIV-I and HIV-II, have been reproducibly isolated in patients with AIDS, and similar conditions such as the AIDS-related complex (ARC) and persistent general lymphadenopathy.

Although a number of nucleosides are known to be useful in treating conditions associated with HIV infection, only zidovudine (AZI, Retrovir) has a regular license for use in the treatment of such conditions. However, zidovudine is known to have serious side effects that affect the normal formation of bone marrow leading to an overall decrease in white blood cell counts leading to anemia, and there is a need for an effective agent that is less cytotoxic.

We have now found a new class of nucleoside analogues with antiviral activity. In a first aspect, a compound of formula (I) is provided according to the thorns:

• N / V \\

I i.

Λ / \ /

Z N N (I)

HO-CHu in which X is hydrogen, NRr \ SR, OR or halogen;

1

Z is hydrogen, OR or NRR;

2

R, R and R may be the same or different and are selected from hydrogen, C 1-6 alkyl and aryl; and its pharmaceutically acceptable derivatives.

Those skilled in the art will know that the compounds of formula (I) are cis compounds and that the cyclopentane ring of compounds of formula (I) contains two chiral centers (represented by * in formula (I)) and can thus exist in the form of two optical isomers (i.e. enantiomers) and mixtures thereof including racemic mixtures.

All such isomers and mixtures thereof are included within the scope of the present invention. Thus, in the compounds of formula (I), any chiral center to which the base may be attached, in the R configuration, and a chiral center to which the group Ct ^ OH is attached, in the S configuration (hereinafter D isomer) or is a chiral center for which is a bonded base in the S configuration, and one to which a Cl ^ OH group is attached in the R configuration (hereinafter referred to as the L isomer). The compounds are suitably either in the form of a racemic mixture or as a pure D isomer. The D isomers can be represented by the formula (Ia)

• ·

Z N N '\ / (1a) in which X and Z are defined as for formula (I). Hereinafter, compounds of formula (I) include compounds of formula (Ia).

It will also be apparent to those skilled in the art that certain compounds of formula (I) can be appreciated in multiple tautomeric forms, and all such tautomers are included within the scope of the present invention.

The term halogen used herein refers to fluorine, chlorine, bromine and iodine; when X is halogen, it is preferably chlorine.

The term C 1-6 alkyl used herein refers to a straight or branched chain alkyl group, for example methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl and t-butyl. Suitably a C 1-6 alkyl group is methyl.

The term aryl used herein refers to any mono- or polycyclic aromatic nucleus and includes substituted and unsubstituted aryl (such as phenyl, tolyl, xylyl, anisyl) and unsubstituted and substituted aralkyl including ar (O _1-4 ) alkyl such as phen (C 1-6) alkyl, for example benzyl or phenethyl.

In the compounds of formula (I), Z is preferably amino.

In a preferred class of compounds of formula (I), X is OR, especially OH.

In a further preferred class of compounds of formula (I) X is NRR and in particular NH ₂ , or hydrogen.

Particularly preferred compounds of formula (I) are those wherein Z is a group of NH ₂ and X is H, NH ₂ or, in particular, OH. These compounds have particularly desirable therapeutic indications as antiviral agents.

The term pharmaceutically acceptable derivatives means any pharmaceutically acceptable salt, ester, or salt of such ester, a compound of formula (I) or any other compound which, upon administration to a recipient, is capable of providing, directly or indirectly, a compound of formula (I) or its antiviral metabolite or residue.

Preferred esters of the compounds of formula (I) include carboxylic acid esters wherein the non-carboxylic portion of the ester group is selected from hydrogen, straight or branched alkyl (e.g. methyl, ethyl, n-propyl, t-butyl), alkoxyalkyl (e.g. methoxymethyl). aralkyl (e.g. benzyl), aryloxyalkyl (e.g. phenoxymethyl), aryl (e.g. phenyl optionally substituted by halogen, C1-6alkyl or C1-6alkoxy); sulfonate esters such as alkyl or aralkylsulfonyl (e.g. methanesulfonyl); amino acid esters (e.g., L-valyl or L-isoleucyl) and mono-, di- or triphosphate esters.

With respect to the esters described above, unless otherwise indicated, any alkaline alkyl moiety suitably contains 1 to 18 carbon atoms, in particular 1 to 4 carbon atoms. Any aryl moiety present in such esters suitably comprises a phenyl group.

The pharmaceutically acceptable salts of the compounds of formula (I) include those derived from pharmaceutically acceptable inorganic and organic acids and bases. Examples of suitable acids include hydrochloric, hydrobromic, sulfuric, nitric, perchloric, formic, maleic, phosphoric, glycolic, lactic, amber, toluene-p-sulfonic, tartaric, acetic, liminic, methanesulfonic, formic, benzoulfonic, malonic, malonic, 2-olone, malonic benzolsulfonic acid. Other acids such as oxalic, although not themselves pharmaceutically acceptable, may be useful in preparing salts useful as intermediates for the preparation of the compounds of the invention and their pharmaceutically acceptable acid addition salts.

Salts obtained from suitable bases include salts of alkali metals (e.g. sodium), alkaline earth metals (eg magnesium), ammonium and NR ^ ⁺ (where R is a group (C ^^) ·

The compounds of the invention will further include compounds of formula (I) and their pharmaceutically acceptable derivatives.

Specific compounds of formula (I) include: (1-alpha, 4-alpha) -4- (6-Chloro-9H-purin-9-yl) -2-cyclopentenylcarbonyl;

(1-alpha, 4-alpha) -4- (6-Hydroxy-9H-purin-9-yl) -2-cyclopentenyl-carbinol;

(1-alpha, 4-alpha) -4- (6-Amino-9H-purin-9-yl) -2-cyclopentenylcarbinol;

(1-alpha, 4-alpha) -4- (6-Mercapto-9H-purin-9-yl) -2-cyclopentenyl-carbinol;

(1-alpha, 4-alpha) -4- (2-Amino-6-chloro-9H-purin-9-yl) -2-cyclopentenyl-carbinol;

(1-alpha, 4-alpha) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenyl-carbinol;

(1-alpha, 4-alpha) -4- (2,6-Diamino-9H-purin-9-yl) -2-cyclopentenyl-carbinol;

in the form of racemic mixtures or simple enantiomers.

The compounds of the invention either themselves have antiviral activity and / or are metabolized to such compounds. These compounds are particularly effective in inhibiting the replication of retroviruses, including human retroviruses such as human immunodeficiency viruses (HIV), agents that cause AIDS.

Some compounds of the invention have anticancer activity, especially those with z being hydrogen.

Thus, in a further aspect of the present invention there is provided a compound of formula (I) or a pharmaceutically acceptable derivative thereof for use as an active therapeutic agent, especially as an antiviral agent, for example in the treatment of a retroviral infection, or an anticancer agent.

In a further alternative aspect there is provided a method of treating viral infections, in particular infections caused by a retrovirus such as HIV, in mammals including humans, comprising administering an effective amount of an antiviral compound of formula (I) or a pharmaceutically acceptable derivative thereof.

In a further alternative aspect, the use of a compound of formula (I) or a pharmaceutically acceptable derivative thereof in the manufacture of a medicament for the treatment of viral infections or use as an anticancer agent is also provided.

The compounds of the invention having antiviral activity are also useful in the treatment of AIDS-related conditions such as the AIDS-related complex (ARC), general progressive lymphadenopathy (PGL), AIDS-induced neuralgic conditions (such as dementia or tropical paraparesis). anti-HIV antibody positive states and HlV-positive states, Kaposi's sarcoma, and thrombocytopenia of purpura.

The antiviral compounds of the invention are also useful in the prevention of the progressive clinical disease of individuals who have positive anti-HIV antibodies or who are positive for HIV and in prophylaxis after exposure to HIV.

The antiviral compounds of formula (I) or their pharmaceutically acceptable derivatives may also be used to prevent viral contamination by saline fluids such as blood or sperm in vitro.

Certain compounds of formula (I) are also useful as intermediates in the preparation of other compounds of the invention.

It will be apparent to those skilled in the art that, within the scope of the present invention, treatment is provided for both prophylaxis and treatment of an established infection or symptom.

It is further understood that the required amount of a compound of the invention for use in treatment will vary not only depending on the particular compound selected but also on the route of administration, the nature of the condition being treated and the age and condition of the patient and depending entirely on the physician or veterinarian.

In general, however, the appropriate dosage will be in the range of about 1 to about 750mg / kg e.g. from about 10 to about 750mg / kg body weight per day, such as from 3 to about 120mg per kilogram body weight of the recipient per day, preferably in the range of 6 to 90 mg / kg / day, most preferably in the range of 15 to 60 mg / kg / day.

The green dose may conveniently be presented in unit dosage form or in divided doses administered at appropriate intervals, for example as two, three, four or more sub-doses per day.

The compounds are suitably administered in unit dosage form; containing for example 10 to 1500mg, preferably 20 to 100mg, most preferably 50 to 700mg of active ingredient per unit dosage form.

Ideally, the active ingredient is administered so as to reach a peak plasma concentration of the active ingredient from about 1 to about 85 / µM, preferably about 2 to 50 / µM, preferably about 3 to about 30 / µM. This may, for example, be achieved by intravenous injection of 0.1 to 5% solution of the active ingredient, optionally in saline solution, or by oral administration in the form of a bolus containing about to about 100 mg / kg of active ingredient. Preferred blood levels can be maintained by continuous infusion to provide about 0.01 to about 5.0 mg / kg / h or alternating infusions containing about 0.4 to about 15mg / kg of active ingredient.

Although it may be possible for the compound of the invention to be administered as a crude chemical for use in treatment, it is desirable that the active ingredient be in the form of a pharmaceutical preparation.

The invention further provides a pharmaceutical composition comprising a compound of formula (I) or a pharmaceutically acceptable derivative thereof together with one or more pharmaceutically acceptable carriers and, where appropriate, other therapeutic and / or prophylactic ingredients. Carriers must be 'acceptable' in terms of compatibility with other ingredients of the preparation and must not be harmful to the recipient.

Pharmaceutical preparations include those suitable for oral, rectal, nasal, superficial (including buccal and sublingual), vaginal or parenteral (including intramuscular and intravenous) administration or in a form suitable for administration by inhalation or infusion. Preparations can. when necessary, it is appropriate to be in separate unit doses and can be prepared by any of the methods known in the art and pharmacy. All methods involve the degree of coupling of the active compound to liquid carriers or finely divided solid carriers, or both, if necessary, of forming the product into desired formulations.

Pharmaceutical formulations suitable for oral administration may conveniently be in the form of separate units such as capsules, cachets or tablets, each containing a predetermined amount of the active ingredient; as powder or granules; as a solution, suspension or as an emulsion. The active ingredient may also be presented in the form of a bolus, candy or paste. Tablets or capsules for oral administration may contain conventional excipients such as binders, fillers, lubricants, disintegrants, or wetting agents. The tablets can be coated according to methods well known in the art. Liquid preparations may be in the form of, for example, aqueous or oleaginous suspensions, solutions, emulsions, syrups or elixirs, or they may be dry products for constitution with water or other suitable carrier before use. Such liquid preparations may contain conventional additives such as suspending agents, emulsifiers, non-aqueous carriers (which may include edible oils), or condoms.

The compounds of the invention can also be formulated for parenteral administration (eg by injection, for example bolus injection or continuous infusion) and may be presented as a unit dose in ampoules pre-filled with syringes or in the form of multidose vessels with added condoms. The compositions may be in such forms as suspensions, solutions, or emulsions in oil or aqueous carrier, and may contain formulating agents such as suspending and / or dispersing agents. Alternatively, the active ingredient may be in powder form, obtained by aseptic isolation of a sterile solid or lyophilization from solution, for constitution with a suitable carrier, e.g. sterile pyrogen-free water before use.

For surface application to the epidermis, the compounds of the invention may be formulated as oils, creams or lotions, or as a transdermal coating. Ointments and creams may, for example, be formulated with a water or oil base with the addition of suitable thickening and / or gelling agents. Lotions can be formulated with an aqueous or oily base and will usually also contain one or more emulsifying agents, stabilizing, dispersing, suspending, thickening or coloring agents.

Formulations suitable for administration externally to the mouth include suction tablets containing the active ingredient in the flavor base, usually sucrose and acacia or tragacanth; lozenges containing the active ingredient in an inert base such as gelatin and glycerin or sucrose or acacia; and a mouthwash solution comprising the active ingredient in a suitable liquid carrier.

Pharmaceutical compositions suitable for rectal administration in which the carrier is solid are most preferably in the form of suppositories as unit doses. Suitable carriers include cocoa butter and other materials commonly used in science, and suppositories can be suitably formed by mixing the active compound with a softened or melted carrier (s) after cooling and molding.

Formulations suitable for vaginal administration may be in the form of pessaries, tampons, creams, jellies, lozenges, foams, or sprays that also contain suitable carriers known in the art.

For intra-nasal administration, the compounds of the invention can be used as a liquid spray or as a drop.

The drops may be formulated with an aqueous or non-aqueous base which also comprises one or more dispersing agents, dissolving agents or suspending agents. Liquid sprays are conveniently obtained from pressure packs.

For administration by inhalation, the compounds of the invention are conveniently delivered from an insulphator, nebulizer or pressurized package or other suitable aerosol dispenser. Pressure packs may include suitable propellant such as dichlorofluoromethane, trichlorofluoromethane, dichlorotetrafluoromethane, carbon dioxide or other suitable gas.

In the case of pressurized aerosols, the unit dose can be determined by means of a valve for dispensing a metered amount.

Alternatively, by inhalation or insufflation, the compounds of the invention may be in the form of dry powder preparations, for example a powder mixture of compounds and a suitable powder base such as lactose or starch. The powder preparation may be in unit dosage form, for example, capsules or casings or e.g. gelatinous or blister packs from which the powder may be administered by inhaler or insufflator.

If desired, the formulations described above can be adjusted to give a delayed release of the active ingredient.

The pharmaceutical compositions of the invention may also contain other active ingredients such as antimicrobial agents or condoms.

The compounds of the invention may also be used in combination with other therapeutic agents for example other anti-infective agents. The compounds of the invention may in particular be used in conjunction with known antiviral agents.

The invention thus provides, in a further aspect, a combination comprising a compound of formula (I) or a physiologically acceptable derivative thereof together with other therapeutically active ages, in particular antiviral ages.

The above-mentioned combinations can be conveniently presented for use in the form of pharmaceutical formulations and such pharmaceutical formulation comprises the combination described above together with a pharmaceutically acceptable carrier and constitutes a further aspect of the invention.

Suitable therapeutic agents for use in such combinations include acyclic nucleosides such as aciclovir, interferons such as alpha-interferon, renal secretion inhibitors such as probenicide, nucleoside transfer inhibitors such as dipyridamole, 2 ', 3'-dideoxynucleosides such as are 2 ', 3'-dodoxycytidine, 2', 3'-dideoxyadenosine, ', 3'-dideoxynosin, 2', 3'-dideoxythymidine and 2 ', 3'-dideoxy2', 3'-didehydrothymidine and immunomodulators such is interleukin II (IL2) and granulocyte macrophage colony stimulating factor (GM-CSF), erythropoietin and empligen.

The individual components of such a combination may be administered one after the other, or simultaneously in separate or combined pharmaceutical formulations.

When a compound of formula (I) or a pharmaceutically acceptable derivative thereof is used in combination with another therapeutically active agent against the same virus, the dose of each compound may be different from that of the compound alone. Proper dosages will be readily determined by one skilled in the art.

The compound of formula (I) and its pharmaceutically acceptable derivatives may be prepared by any method known in the art for the preparation of analogous structures.

Suitable methods for preparing the compound of formula (I) and its pharmaceutically acceptable derivatives are described below; groups X and Z are defined as above unless otherwise indicated. It is understood that the following reactions may require application, or may be suitably applied, to starting materials having protected functional groups, and thus may need to be deprotected at the intermediate or final stage to obtain the desired compound.

Protection and deprotection of functional groups can be performed using conventional methods. Thus, for example, amino groups may be protected by a group selected from aralkyl (e.g., benzyl), acyl or aryl (e.g., 2,4-dinitrophenyl); the subsequent removal of the protecting group may be carried out when desired by hydrolysis or hydrogenolysis, as appropriate, using standard conditions. Hydroxyl groups can be protected using any conventional hydroxyl group protecting group, for example, as described in 'Protective Groups in Organic Chemistry', Ed.JFWMcOmie (Plenum Press, 1973) or 'Protective Groups in Organic Synthesis by Theodore W.Greene (John Wiley and Sons, 1981). Examples of suitable protecting groups for hydroxyl 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). Hydroxyl protecting groups can be removed by conventional techniques. Thus, for example, alkyl, silyl, acyl and heterocyclic groups can be removed by solvolysis, e.g. by hydrolysis under acidic or basic conditions. Aralkyl groups such as triphenylmethyl can be similarly removed by solvolysis, e.g. by hydrolysis under acidic conditions. Aralkyl groups such as benzyl can be cleaved by hydrogenolysis in the presence of a catalyst for cast metal such as palladium on coal. The silyl groups can also be conveniently removed by the use of fluoride ion sources such as tetra-n-butylammonium fluoride.

In the first process (A), compounds of formula (I) and their pharmaceutically acceptable derivatives can be obtained by reaction of compounds of formula (II) / /

N

I. »

Λ \ Λ with N ΝΗ (II)

HO-CH.

(wherein X and Z are substituents having the meanings of formula (I) or in a protected form, and the hydroxyl group in the cyclopentenylcarbinol group may be in a protected form) or a pharmaceutically acceptable derivative thereof, with a reagent selected from formic acid and its reactive derivatives , after which, if necessary, the unwanted groups introduced into said reagent are removed and / or any protecting groups present are removed.

Examples of suitable formic acid derivatives that can be used in process (A) above include orthoformats (e.g. triethyl orthoformate), dialkoxymethyl acetates (e.g. diethoxymethyl acetate), dithio formic acid, formamide, s-triazine or formamidine acetate.

The undesirable groups induced by formic acid or its reactive derivative may conveniently be removed by gentle hydrolysis, for example by the use of an inorganic acid such as aqueous hydrochloric acid.

When a trialkyl orthoformate is used, such as triethyl orthoformate, it is also a suitable reaction solvent. Other solvents that may be used include amides (e.g. dimethylformamide or dimethylacetamide), chlorinated hydrocarbons (e.g. dichloromethane), ethers (e.g. tetrahydrofuran) or nitriles (e.g. acetonitrile).

In some cases (eg when using a trialkyl orthoformate such as triethyl orthoformate) the reaction may conveniently be carried out in the presence of a catalyst such as a light acid (eg concentrated hydrochloric, nitric or sulfuric acid). The reaction can be carried out at a temperature in the range of -25θΟ to + 150θ0, e.g. Οθ to ΙΟΟθΟ, and to the right at ambient temperature.

In the second process (B), the compounds of formula (I) and their pharmaceutically acceptable derivatives or their protected form are subjected to interconversion reactions whereby the initially substituted substituent X is replaced by a different substituent X and / or the originally present group Z is replaced by another group Z after which, when necessary, any protecting groups present are removed.

In one embodiment of method (B), compounds of formula (I) in which X represents the group RR '(where R and R' are defined as before) can be obtained by amination of a corresponding compound of formula (I) in which X represents a halogen atom (e.g. .hlora). The amination can be carried out by reaction with the reagent HNRR '(in which R and R' are defined as before), suitably in a solvent such as alcohol (eg methanol). The reaction can be carried out at any suitable temperature, preferably at elevated temperature such as under reflux or, when using liquid ammonia, in a sealed tube at about 50θ to 80θ (2. Suitable conditions for the conversion of halides and secondary and tertiary amines are also described IIHarrison et.al., Compendium of Organic Synthetic Methods, Wiley-Interscience, Nev. York (1971) pp. 250-252.

In another embodiment of process (B), compounds of formula (I) in which X represents the group OR (where R is defined as before) can be obtained by substituting a halogen atom (e.g., chlorine) with the corresponding anion RO. When R represents a hydrogen atom, the substitution reaction may be carried out by hydrolysis which may be carried out in water or in a mixture of water and in the water of a solvent such as alcohol (eg methanol or ethanol), ether (e.g. dioxane or tetrahydrofuran), ketone (e.g. acetone), an amide (e.g. dimethylformamide) or sulfoxide (e.g. dimethylsulfoxide), optionally in the presence of an acid or base. Suitable acids include organic acids such as p-toluenesulfonic acid and inorganic acids such as hydrochloric, nitric or sulfuric acids.

Suitable bases include inorganic bases such as alkali metal hydroxides or alkali metal carbonates (e.g. sodium or potassium hydroxide or carbonate). Aqueous acids or bases can also be used as a reaction solvent. Hydrolysis can conveniently be carried out at a temperature in the range of -10 ° to + 150 ° C, e.g. on reflux. When R represents a C 1-6 alkyl or aryl group, the anion RO is suitably formed from the corresponding ROH alcohol using an inorganic base such as an alkali metal (e.g. sodium metal) or an alkali metal hydride (e.g. sodium hydride). The reaction with an in situ formed anion can conveniently be carried out at ambient temperature.

In a further embodiment of process (B), compounds of formula (I) in which X represents a group SH can be obtained by reaction with a halo compound of formula (I) with a thiourea in a suitable solvent such as alcohol (e.g. n-propanol) at elevated temperature ( eg reflux) followed by alkaline hydrolysis. Suitable bases that may be used include alkali metal hydroxides (eg sodium hydroxide). The reaction may conveniently be carried out according to the method of G.G. Utquart et.al. Org.Syn.Coli.Vol.2 / 363 (1953) e.g. by refluxing an intermediate with aqueous NaOH for about 0.25 to about 5 hours.

In another embodiment. method (B), compounds of formula (I) in which X represents a hydrogen atom can be obtained by reducing the halo compounds of formula (I) using a reduction system that will not affect the rest of the molecules. Suitable reducing agents that can be used to induce the green dehalogenation reaction include metal zinc / water according to the method described by J. R. Marshall et al., J. Chem.Soc. ,

1004 (1951). Alternatively, the reaction may be carried out by photolysis in a suitable solvent such as tetrahydrofuran containing 10% triethylamine and, optionally, in Rayonet's photochemical reactor (2537A) according to the method of V.Nair et.al., J.Org.Chem.

52, 1344 (1987).

In another embodiment of process (B), compounds of formula (I) in which X represents a halogen atom can be obtained from various halo compounds of formula (I) by conventional halogen-halogen exchange methods. Alternatively, when X is chlorine, this substituent can be replaced by other halogen atoms by applying different p- (halo) benzene diazonium chloride according to known procedures.

Compounds of formula (I) in which X represents an SR group in which R is a C 1-6 alkyl or aryl group can be prepared from the corresponding thiols using standard alclation or aryl methods, as described for example in US Patent No. 4,383,114.

Compounds of formula (I) in which Z represents a hydroxyl group can conveniently be obtained from a corresponding compound of formula (I) in which Z represents NH _{2 by} reaction with nitric acid, for example by using the procedure used by

J.Davoll in J.Amer.Chem.Soc., 73, 3174 (1951)

Many of the reactions described above have been extensively described in the context of the synthesis of purine nucleosides, for example in Nucleoside Analogs - Chemistry, Biology and Medical Applications, R.T. Walker et.al., ed. Plenum Press, New York (1979) at p.

193-223, the description of which is herein incorporated by reference.

The pharmaceutically acceptable salts of the compounds of the invention can be prepared as described in US Patent No. 4,383,114, the description of which is incorporated herein by reference. Thus, for example, in order to obtain the acid addition salt of the compounds of formula (I), the product of any of the above procedures can be converted to a salt by treating the resulting free base with a suitable acid using conventional methods.

Pharmaceutically acceptable acid addition salts can be prepared by reacting the free base with the appropriate acid as needed in the presence of a suitable solvent such as ether (eg ethyl acetate) or alcohol (eg methanol, ethanol or isopropanol). The non-oranic base salts can be obtained by reacting the free base with a suitable base such as alkoxide (e.g. sodium methoxide) as needed in the presence of a solvent such as alcohol (eg methanol). Pharmaceutically acceptable salts may also be prepared from other salts, including other pharmaceutically acceptable salts, of the compounds of formula (I) using conventional methods.

The compounds of formula (I) may be converted to pharmaceutically acceptable phosphates or other streams by reaction with a phosphorylating agent such as POCl 4 or a suitable esterifying agent such as a halide or anhydride of acid, as appropriate. The ester or salt of the compounds of formula (I) can be converted to the parent compound, for example by hydrolysis.

The compounds of formula (II) and their salts are novel compounds and constitute a further aspect of the present invention.

Compounds of formula (II) in which Z is hydrogen or hydroxyl can be obtained directly from compound 2a by reaction with

• · • 2a excess pyrimidine of formula (III) / A / ^H2

N.

I II

Λ \ A

Z N Y (III) (in which Y is a halogen atom, e.g. chlorine and Z is hydrogen or hydroxyl) in the presence of an amine base such as triethylamine and in an alcoholic solvent (e.g. n-butanol), optionally at reflux.

Compounds of formula (II) in which Z represents NH ₂ can be obtained by using compounds of formula 2a by reaction with an excess of pyrimidines of formula (IV)

X

I / A

N t II (IV)

Λ \ Λ h ₂ nny (in which Y is defined as above in formula (III)) under similar conditions as described above to obtain compounds of formula (II) in which Z is hydrogen or hydroxyl, to give a compound of formula ( V) // \ - v

H ₂ N \ 'H

HO-CH.

\ / \ (V) which can be diazotized using the diazonium salt ArN ₂ ⁺ E (where Ar represents an aromatic group, e.g. p-chlorophenyl, and E “represents an anion, e.g., halogen such as chloride) in a solvent such as water, an organic acid such as acetic acid or mixtures thereof, preferably at about ambient temperature, to give the compound of formula (VI)

X h ₂ n; / \\ / \

N NH

HO-CH ₉ '. ² \ / \ (VI) (wherein Ar is defined as above) which can be converted into the desired compound of formula (II) by reduction using for example a reducing metal such as zinc in the presence of an acid, e.g. acetic acid. It is understood that the choice of reducing agent will depend on the nature of Group X.

Compound 2a can be obtained from a versatile precursor, 1-alpha-acetylamino-3-alpha-acetoxy-methylcyclopent-2-ene (1a) hydrolysis in the presence of a mild base such as alkaline earth metal hydroxide.

A particularly suitable synthesis of the compound of formula (I) via the 6-chloro compound of formula (II) is given below.

- 18 Cl. NH ₇ // \ / ²

N ·

I »z ^A V \ h

«Χ / ·

3a

Cl i

5a

A

6a / Λ Λ

N · \

CH

Cl

I

i

4a

Compound 2a and compounds of formulas (V) and (VI) are novel intermediates and further aspects of the present invention.

Compound 1a is a known compound described in US Patent No. 4,138,562.

When the compound of formula (I) is desired in the form of a single isomer, it can be obtained either by decomposition of the final product or by stereospecific synthesis from isomerically pure starting materials or a suitable intermediate.

The decomposition of the final product, or intermediate or starting material can be done in any suitable manner known in the art: see, for example, ¹ Stereochemistry of Carbon Compounds' by ELEliel (McGraw Hill, 1962) and 'Tables of Resolving Agents' by SHWilen- a.

One suitable method for the preparation of chirally pure compounds of formula (I) is the enzymatic conversion of the racemic mixture of the compound or its precursor. In this optically pure (+) and (-) compounds of formula (I) can be obtained in optically pure form. Suitable enzymes include deaminases such as adenosine deaminase.

The invention will be further described with reference to the following detailed examples for which elemental analyzes were performed at MHW Laboratories, Phoenix, AZ. Melting points were determined in a Mel-Temp apparatus and corrected. Nuclear magnetic resonance spectra were obtained in Joel FX 90QFT or Nicollet NT300 spectrometers and recorded in DMSO-Dg. The chemical shifts are expressed in ppm downstream of Me ^ Si. IR spectra were determined with KBr pellets with a Nicollet 50XC Fi-IR spectrometer, and UV spectra were determined in a Beckmann DU-8 spectrophotometer. Mass spectra were obtained on an AEI Scientific Apparatus Limited MS-30 mass spectrometer. Thin layer chromatography (TLC) was performed on 0.25mm layers of Merck silica gel (230-400 mesh). All chemicals and solvents are reagent grade unless otherwise noted. The term 'active ingredient ¹ , as used in the Examples, denotes a compound of formula (I) or a pharmaceutically acceptable iv derivative thereof.

Example 1 (i) - (1-alpha, 4-alpha) -4 - ((5-Amino-6-chloro-4-pyrimidinyl) -amino] -2-cyclopentenylcarbinol (3a)

A mixture of 1-alpha-acetylamino-3-alpha-acetoxymethyl cyclopent 2-ene (1a) (3.0g, 15mmol) and aqueous barium hydroxide (0.5N, 300ml) was refluxed overnight. After cooling, it was neutralized with dry ice. The precipitate was graded and the aqueous solution was concentrated to dryness. The residue was extracted with absolute ethanol and concentrated again to give 2a as a colorless syrup of 1.6g (14mmol).

To this syrup was added 5-amino-4,6-dichloropyrimidine (4.59g, 28 mmol), triethylamine (4.2g, 42 mmol), and n-butanol (50ml) and the mixture was refluxed for 24 h. Evaporative solvents were removed, the residue was absorbed on silica gel (7g), packed in a column (4.0 x 12cm) and eluted with CHCl3-MeOH (20: 1) to give 2.69g (74%) of compound 3a; mp 130-132 ° C. The analytical sample was obtained by crystallization from ethyl acetate (EtOAc), mp 34-135 ° C, MS (30 ev, 200 ° C); m / e 240 and 242 (M ⁺ +2), 209 (M ⁺ 31), 144 (B ⁺ ); IR: 3600-2600 (OH), 1620, 1580 (C = C, C = N); Anal. (C ₁₀ H ₁₃ ClNO ₄ O) C, N, N

Example 2 (i) - (1-alpha, 4-alpha) -4 - [(2-Amino-6-chloro-4-pyrimidinyl) -amino] -2-cyclopentenylcarbinol (4a)

2-amino-4,6-dichloro-pyrimidine (3.74g, 22.8 mmol), triethylamine (15ml) and n-butanol (75ml) were added to 14 mmol of crude 2a (Example 1) and the mixture was refluxed for 48 h. The volatile solvents were removed, the residue was treated with methanol to separate insoluble by-products (double pyrimidine nucleoside). The methanolic solution was absorbed on silica gel (8g), packed in a column (4.0 x 14cm) and eluted with CHCl3-MeOH (40: 1) to give 1.52g (42%) to crude 4a. The product was recrystallized from ethyl acetate to give 4a; mp 132-134 ° C, MS (30 ev, 200 ° C); m / e 240 and 242 (M ⁺ 1 2), 209 (M ^{+ -} 31), 144 (B +); IR: 3600-3000 (NH _2, OH), 1620.1580 (C = C,

C = N); Anal. ( ^c 10 ^H 13 ^clN 4) C, H, N.

Example 3 (t) - (1-alpha, 4-alpha) -4 - ([(2-Amino-6-chloro-5- (4-chlorophenyl) -azo] 4-pyrimidinyl-antino) -2-cyclopentenylcarbinol ( 5a)

A cold solution of diazonium salt was prepared from p-chloroaniline (1.47g, 11.5 mmol) in 3N HCl (25ml) and sodium nitrite (870mg, 12.5 mmol) in water (10ml). This solution was added to a mixture of 4a (2.40g, 10mmol), acetic acid (50ml), water (50ml) and sodium acetate trihydrate (20g). The reaction mixture was stirred overnight at room temperature. The yellow precipitate was treated and washed with cold water to neutral, then air-dried in the reaction to give 3.60g (94%), 5a, mp 229 ° C (dec.). The analytical sample was obtained from acetone-methanol (1: 2), mp241-243 ° C (dec.). MS (30 ev, 260 ° C): m / e 378 and 380 (M ⁺ + 2), 282 (B ⁺ ); IR: 3600-3000 (NH ₂ OH), 1620, 1580 (C = C, C = N);

Anal. (C ₁₆ H _lg Cl ₂ N ₆ O) C, H, N.

Example 4 (-) - (1-alpha, 4-alpha) -4 -, [(2,5-Diamino-6-chloro-4-pyrimidinyl) -amino]

2-cyclopentenylcarbinol (6a)

A mixture of 5a (379mg, 1mmol), zinc powder (0.65g, 10mmol), acetic acid (0.32ml), water (15ml) and ethanol (15ml) was refluxed under nitrogen for 3 hours. The zinc was removed and the solvents were evaporated. The residue was absorbed on silica gel (2g), packed on a column (2.0 x 18cm), and eluted with CHCl3-MeOH (15: 1). Pink syrup was obtained. Further purification from methanol-ether gave 6a as pink crystals, 170mg (66%), mp 68-170 ° C, MS (30 ev, 22 ° C); m / e 255 and 257 (M ⁺ and M ⁺ + 2), 224 (M ⁺ ”31), 159 (B ⁺ ); IR: 3600-3000 (NH ₂ OH)

1620, 1580 (C = C, C = N); Anal. (C ^ H ^ ClNg) C, H, N.

Example 5 (±) - (1-alpha, 4-alpha) -4- (6-Chloro-9H-purin-9-yl) -2-cyclopentenylcarbinol (7a)

A mixture of 3a (1.30g, 5.4 mmol), triethyl orthoformate (30 ml) and hydrochloric acid (12N, 0.50ml) was stirred overnight at room temperature. The solvent was evaporated at 35 ° C under vacuum. Aqueous hydrochloric acid (0.5 N, 30ml) was added to the residue and the mixture was stirred for 1 h, the mixture was neutralized to pH 7-8 with 1N sodium hydroxide and absorbed on silica gel (8g), suspended in a column (4.0 x 8cm). , and eluted with CHCl3-MeOH (20: 1) to give white crystals 7a, 1.12g (82%). The crude product was recrystallized from ethyl acetate to give 7a, mp 108-110 ° C, MS (30 ev, 200 ° C); m / e 250 and 252 (M ⁺ and M ⁺ + 2), 219 (M ⁺ 31), 154 (B ⁺ ); IR? 3600-2800 (OH), 1600 (C = C, C = N); Anal. (C ^ H- ^ CII ^ O)

C, H, N.

Example 6 (±) - (1-alpha, 4-alpha) -4- (6-Hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol (8a)

A mixture of 7a (251mg, 1mmol) and aqueous sodium hydroxide (0.2N 10ml) was refluxed for 3 h. After cooling, the reaction mixture was adjusted to pH 5-6 with acetic acid. The reaction mixture was absorbed on silica gel (2g) packed in a column (2.0 x 11cm) and eluted with CHCl3-MeOH (10: 1) to give 105mg (45%) of 8a. The crude white product was crystallized from water-methanol (3: 1) to give 8a, mp 248-250 ° C (dec.), MS (30 ev, 300 ° C); m / e 232 (M ⁺ ), 214 (M ^T &^lt; 18 &^gt;), 136 (B ⁺ ); 3600-2600 (OH), 1680.1600 (C = O, C = C, C = N); Anal. (C ₁₁ H ₁₂ N ₄ O ₂ ) C, H, N.

Example 7 (±) - (1-alpha, 4-alpha) -4- (6-Amino-9H-purin-9-yl) -2-cyclopentenylcarbinol (9a)

Liquid ammonia was passed through a bomb with a solution of 7a (250mg, 1mmol) in methanol (5ml) at -80 ° C. The bomb was sealed and heated at 60 ° C for 24 h. Ammonia and methanol were evaporated and the residue was recrystallized from water to give off-white crystals 9a, 187mg (81%), mp 198- 200 ° C.MS (30 ev, 210 ° C): m / e 231 (M ⁺ ), 213 (M ⁺ ~ 18), 135 (B ⁺ ); IR: 3600-2600 (NH _2, OH), 1700.1600 (C = C, C = N); Anal. (C ₁₁ H ₁₃ N ₅ O) C, H, N.

Example 8 (±) - (1-alpha, 4-alpha) -4- (6-Mercapto-9H-purin-9-yl) -2-cyclopentenyl carbinol (10a)

A mixture of 7a (125mg, 0.5mmol), thiourea (40mg, 0.64mmol) and n-propanol (5ml) was refluxed for 2 h. After cooling, the precipitate was isolated by filtration, washed with n-propanol, and dissolved in sodium hydroxide (IN, 5ml). The solution was adjusted to pH 5 with acetic acid. The crude lOa (90mg, 73%) was again isolated, mp 260-262 ° C (dec.) And recrystallized from N, N-dimethylformamide to give lOa, mp 263-265 ° C (dec.). MS (30 eV, 290 ° C): m / e 248 (M ⁺ ), 230 (M ⁺ ~ 18), 152 (B ⁺ ); IR: 3600-3200 (OH), 3100, 2400 (SH), 1600 (C = C, C = N); Anal. ((^ H ^ OS) C, H, N.

Example 9 (+) - (1-alpha, 4-alpha) -4- (2-Amino-6-chloro-9H-purin-9-yl) -2-cyclopentenyl carbinol (13a)

A mixture of 6a (1.41g, 5.5 mmol) of triethyl orthoformate (30 ml) and hydrochloric acid (12N, 1.40ml) was stirred overnight. The suspension was dried in vacuo. Dilute hydrochloric acid (0.5N, 40ml) was added and the mixture was reacted at room temperature for 1 h. The mixture was neutralized to pH 8 with 1N sodium hydroxide and absorbed on silica gel (7.5g) packed in a column (4.0 x 10cm) and eluted with CHCl2-MeOH (20: 1) to give off-white crystals 13a, 1.18g (80 %). The crude product was recrystallized from ethanol to give 13a, mp 145-147 ° C.MS (30 ev, 220 ° C): m / e 265 and 267 (M ⁺ and M ⁺ + 2), 235 (M ⁺ 30), 169 ( B ⁺ ); IR: 3600-2600 (NH ₂ OH), 1620-1580 (C = C, C = N); Anal. (C- ^ H ^^ OCl. 3 / 4H ₂ O) C, H, N.

Example 10 (i) - (1-alpha, 4-alpha) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol (14a)

A mixture of 13a (266mg, 1mmol) and aqueous sodium hydroxide (0.33N) was refluxed for 5 h, absorbed on silica gel (2g) packed in a column (2.0 x 7.5cm) and eluted with CHCl2-MeOH (5: 1).

The crude product was recrystallized from methanol-water (1: 4) to give white crystals 14a, 152mg (61%), mp 254-256 ° C (dec.). MS (30 eV,

200 ° C): m / e 247 (M ⁺ ), 217 (M ⁺ ~ 3 °), 151 (B ⁺ ); IR: 3600-2600 (NH ₂ ,

OH), 1700.1600 (C = O, C = C, C = N); Anal. (C, .H. _O N _c 0 _o .3 / 4H-0) C, H, N.

i 1 i J 5 2 z

Example 11 (i) - (1-alpha, 4-alpha) -4- (2,6-Diamino-9H-purin-9-yl) -2-cyclopentenyl carbinol (15a)

Liquid ammonia was passed into a solution of 13a (265mg, 1 mmol) in methanol (10ml) at -80 ° C in a bomb. The bomb was sealed and heated at 75 ° C for 48 h. Ammonia and methanol were evaporated. The residue was absorbed on silica gel (2g), packed in a column (2.0 x 10cm) and eluted with CHCl3-MeOH (15: 1). The crude product was recrystallized from ethanol to give 196mg (80%) of 15a, mp 152-155 ° C.

MS (30 eV, 200 ° C): m / e 246 (M ⁺ ), 229 (M ⁺ ”17), 216 (M ⁺ ~ 30), 150 (B ⁺ ); IR: 3600-3000 (NH _2, OH), 1700,1650,1600 (C = O, C = C, C = N); Anal. (Ο _χι Η ₁₄ Ν ₆ Ο) C, H, N.

Example 12 (IS, 4R) -4- (2,6-Diamino-9H-purin-9-yl) -2-cyclopentenyl carbinol [(1S, 4R) -4- (2,6-Diamino-9H-purine- 9-yl) -2-cyclopentene methanol] (a) Intermediate 1: (IR, 2S, 3R, 5R) -3- [6-Amino-9H-purin-9-yl] -5 [((1,1- dimethyl) dimethylsilyloxy) methyl] -1,2-cyclopentadiol (-) aristeromycin ^ (12.505g), tert-butyldimethylsilyl chloride (7.8g) and imidazole (12.96g) in dry dimethylformamide (85ml) was stirred at room temperature for 2l / 2h. The resulting solution was diluted with ethyl acetate (500ml), then washed with water (3x100ml) and brine (50ml) before white solid crystals began to appear. These were collected by filtration, washed with ethyl acetate, then dried in vacuo to give the title compound (3.92g); 1H NMR (DMSO-d6) 8.15 (1H), 8.09 (1H), 7.19 (2H), 5.00 (1H),

4.72 (1H), 4.36 (1H), 3.85 (1H), 3.67 (2H), 2.23 (1H), 2.09 (1H), 1.79 (1H), 0.89 (9H), 0.07 (6H).

1. Journal of the American Chemical Socaety 1983, vol.105. 4049-4055.

b) Intermediate 2: (4R, 3aS, 6R, 6aR) -4- [6-Amino-9H-purin-9-yl] -6 [((1,1-dimethylethyl) -dimethylsilyloxy) methyl] -3a, 5 , 6,6a-tetrahydro4H-cyclopenta-1,3-dioxol-2-thione

A mixed suspension of Intermediate 1 (3.45g) in dry dimethylformamide (56ml) was treated with 1,1'-thiocarbonyldiimidazole (3.3g) to give a yellow solution. After 15l / 2h at ambient temperature, the resulting solution was combined with the solution from the previous experiment (6% and the solvent was removed by evaporation. The residual oil was diluted with ethyl acetate (100ml), then washed with water (2x20ml) and brine (2x20ml). This was washed with diethyl ether (25ml), then collected by filtration, further washed with ether (25ml), then dried in vacuo to give the title compound as a pale cream solid (3.61 g); X (ethanol 240.Onm .n -i max (E η 459); H nmr (DMSO-d,) 8.27 (1H), 8.13 (1H), 7.33 (2H), icm o

5.81 (1H), 5.37 (1H), 5.28 (1H), 3.78 (2H), 2.60 (1H), 2.28 (2H), 0.90 (9H), 0.09 (6H).

(c) Intermediate 3: (1'R, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl-2-cyclopenten-1-yl] -9H-purin-6-amine

A solution of Intermediate 2 (3.57g) in dry tetrahydrofuran (25ml) was treated with a solution of 1,3-dimethyl-2-phenyl-1,3,2-diazophospholidine (4.94g) in dry tetrahydrofuran (10ml), then stirred at ambient temperature during 8 ^ / 4h. The solvent was removed by evaporation

The residual oil was combined with the oil of the previous experiment (40%), then subjected to column chromatography on silica (200g, Merck 7734), eluting with chloroform, followed by chloroform-ethanol mixtures to give a white solid. This was washed with diethyl ether (25ml) then collected by filtration.

The solid was further washed with ether (10ml) then dried in vacuo to give the title compound (1.47q); X _____ (ethanol) 261.4nm (E ^X ° 443); 1H nmr (DMSO-d,) 8.14 (1H), solder b

8.00 (1H), 7.20 (2H), 6.12 (1H), 5.95 (1H), 5.60 (1H), 3.66 (2H), 2.96 (1H), 2.69 (1H), 1.65 (1H), 0.74 (9H). 0.02 (6H).

(d) Intermediate 4: (1 ¹ R, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl) -2-cyclopenten-1-yl] -9H-purin-6-amine. 1-Oxide A solution of intermediate 3 (1.37g) in chloroform (30ml) was treated with 80-90% m-chloroperoxybenzoic acid (1.29g), then stirred at ambient temperature for 3 hours. The solvent was removed by evaporation and the residual gum was dissolved in ethyl acetate (10ml). The white solid was crystallized. This solid and the material isolated by evaporation of the filtrate were dissolved in chloroform (lOOml), then washed with saturated aqueous sodium bicarbonate solution (3x10ml) and brine (2x10ml). The aqueous washes were again extracted with chloroform (50ml). The combined organic solutions were dried (MgSO4), then evaporated to a solid. This was washed with diethyl ether (25ml) then collected by filtration. The white solid was further washed with ether (10ml) then dried under vacuum to give

Al% (ethanol) 235.4nm (E, 1324),

1% ΨΙ ^Χ 1 solder

263.2nm (E * 248), 300.2nm (ET 75); H nmr (CDCl 3 _O ) 8.72 lem lem 3 (1H), 8.02 (1H), 7.16 (2H), 6.21 (1H), 5.87 (1H), 5.72 (1H).

3.68 (2H), 3.04 (1H), 2.82 (1H), 1.74 (1H), 0.89 (9H), 0.06 (6H) (e) Intermediate 5: (1'R, 4'S) -7- [4 - (( (1,1-Dimethylethyl) dimethylsilyloxy) methyl) -2-cyclopenten-1-yl) -2-imino-1,2-dihydro- [1,2,4] oxadiazolo- [3,2-i] -9H- purine bromhydrate

A stirred ice-cold suspension of Intermediate 4 (1.08g) in methanol (20ml) was treated with a solution of cyanogen bromide (0.34g) in methanol (20ml) added over 5 minutes. After 15 minutes, the suspension was allowed to warm to ambient temperature, providing a solution. After 90 minutes, the solvent was removed by evaporation. The residue was washed with diethyl ether (25ml) then collected by filtration. The solid was further washed with ether (25ml), then dried under vacuum to give the title compound (1.37g (; l (ethanol) 2-28.2nm (E ¹ ? 530), 285.2nm (eJ ^% 445), - ¼ ^v max lem lem

nmr (CDCl ₃ ) 10.20 (1H), 10.02 (1H), 8.37 (1H), 6.25 (1H),

6.01 (1H), 5.90 (1H), 3.69 (2H), 3.05 (1H), 2.86 (1H), 1.73 (1H) 0.86 (9H), 0.03 (6H).

(f) Intermediate 6: (1'R, 4 ¹ S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl) -2-cyclopenten-1-yl] -6-cyanoimino-1. 6-Dihydrol-methoxy-9H-purine

A solution of Intermediate 5 (1.36g) in dimethylformamide (10ml) was stirred at ambient temperature, then treated with triethylamine (1.2ml). After 40 minutes, iodomethane (0.54ml) was added to give a yellow solution. After 3 ^ / 4h the solvent was removed by evaporation.

The residue was partitioned between ethyl acetate (100 ml) and water (20 ml). The organic solution was further washed with water (2x20ml) and brine (20ml), dried (MgSO4) and evaporated to dryness. The solid residue was washed with diethyl ether (25ml) then collected by filtration. The white solid was further washed with ether (10ml) then dried in vacuo to give the title compound (0-865g); A (ethanol) 227.2nm (eJ ^% 449), · 287.Onm (E * ^% 554);

Amax lem lem

1H NMR 8.23 (1H), 7.96 (1H), 6.24 (1H), 5.85 (1H), 5.65 (1H),

4.21 (3Η), 3.66 (2Η), 3.04 (1H), 2.77 (1H), 1.68 (1H), 0.88 (9H), 0.05 (6H).

(g) Intermediate 7: (1 * R, 4'S) -9- [4 - (((1,1-Dimethylethyl) dimethylsilyloxy) methyl) -2-cyanopenten-1-yl] -6-methoxyamino-9H-purin2- amine

A solution of intermediates 6 (802mg) and 1,8-diazabicyclo [5,4,0] undec7-ene (0.45ml) in ethanol (80ml) was stirred and heated at reflux. Heating was stopped after 9 hours and the solution was left at ambient temperature overnight. The solvent was removed by evaporation. The residual oil was combined with that of the previous experiment (4% purity), then chromatographed on silica gel column (40g, Merck 9385) eluted with chloroform, followed by chloroform-ethanol mixtures to give a foam. This foam was triturated with diethyl ether (10ml) and the resulting solid was collected by filtration. The solid was further washed with ether (5ml), then vacuum-dried to give the title compound (595mg); X _max (ethanol) 282.2nm 409); ^ Hn.mr (DMSO-dg) 9.76 (1H), 7.32 (1H) , 6.53 (2H), 6.08 (1H), 5.88 (1H), 5.26 (1H),

3.72 (3H), 3.61 (2H), 2.90 (1H), 2.50 (1H), 1.52 (1H), 0.83 (9H), 0.02 (6H).

(h) Intermediate 8: (IS, 4R) -4- [2-Amino-6-methoxyamino-9Hpurin-9-yl] -2-cyclopentene-methanol

A solution of Intermediate 7 (356mg) in tetrahydrofuran (35ml) was stirred at ambient temperature and then treated with tetrabutylammonium fluoride (1.0M solution in tetrahydrofuran, 1.4ml). After 90 minutes the reaction was quenched with water (1ml) then the solvents were removed by evaporation. The residual oil was chromatographed on a silica gel column (20g, Merck 7734), eluted with chloroform, then with chloroformethanol mixtures to give the title compound as a solid (243mg); (pH 6 buffer) 280.2nm (E ^ ° 534); ^ H n.m.r.

(DMSO-dg) 9.75 (1H), 7.39 (1H), 6.52 (2H), 6.10 (1H), 5.84 (1H), 5.27 (1H), 4.73 (1H), 3.40 (2H), 2.83 (1H). 2.55 (1H), 1.52 (1H) (1S, 4R) -4- [2,6-Diamino-9H-purin-9-yl] -2-cyclopentenecarbinol

The crushed, ice-cold solution of Intermediate 8 (210mg) in water (10ml) and tetrahydrofuran (50ml) was treated with aluminum amalgam [aluminum (237mg) and 0.5% aqueous mercury chloride solution, added in small pieces over 15 minutes. After 40 minutes, the stirred mixture was allowed to warm to ambient temperature. After 15 hours the resulting mixture was passed through a 'kieselguhr' to remove the insoluble parts. This was washed with water: tetrahydrofuran (1: 5, 60ml). The combined filtrates were evaporated. The residue was chromatographed on a silica column (10g, Merck 9385), eluting with chloroform.ethanol mixtures to give the title compound as a foam (159mg); [alpha] _D ~ 81 ^U (cl-04, methanol);

X (pH 6 buffer) 255. Onm (E, ^% 302), 280.8 nm (E? - ^% 381), tmax ^cc lem lem

H nmr (DMSO-d _g ) 7.61 (1H), 6.66 (2H), 6.10 (1H), 5.87 (1H), 5.76 (2H), 5.38 (1H), 4.76 (1H), 3.45 (2H), 2.87 ( 1H), 2.60 (1H), 1.60 (1H).

Example 13 (IS, 4R) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol (1'R, 4'S) -2-Amino-1,9-dihydro- 9- [4-Hydroxymethyl-2-cyclopenten-1-yl] -6H-purin-6-one

A cloudy solution of the title compound of Example 12 (144g) in

0.1M pH 6 buffer (10ml) (from 28.4g disodium orthophosphate in liters of water, adjusted with orthophosphoric acid) was treated with adenosine diaminase solution (0.5ml, 778 units), in

50% glycerol - 0.01M potassium phosphate, pH 6.0, then stirred and heated to 37 °. After 18 - * - / 2 hours the resulting suspension was cooled in the fridge. The solid collected was recrystallized from water to give the title compound as a white solid (86mg); [alpha] -49 ° (c 0.5, dimethylsulfoxide) (pH 6 buffer) d -, max

252.6nm (E? 531), H nmr (DMSO-d _r ) 10.60. (IH). 7.60 Solder 6 (1H), 6.47 (2H), 6.10 (1H), 5.86 (1H), 5.33 (1H), 4.72 (1H), 3.45 (2H), 2.59 (1H), 1.58 (1H).

Example 14

Purification of the enantiomer of (1-alpha, 4-alpha) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenylcarbinol (a) (IS, 4R) -4- (2-Amino-6 -hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol

Diamino analog (lOOmg) (Example 11) was dissolved in 3ml

0.05M. ^K 2 ^PO 4 P ^u f ^era (pH 7.4) with warming (50 ° C). The solution was cooled to room temperature and 40 units of adenosine diaminase (Sigma, Type VI, bovine intestinal mucosa) were added. After three days of incubation at room temperature, the formed precipitate was removed by filtration, yield 18.2mg. The filtrate was concentrated to 1.5ml and cooled for 2 days in the refrigerator. More solids were obtained by filtration, yield 26.8mg. The two solid fractions were recrystallized from water and the title compound was obtained tt269-272 C, [alpha] _D -62.1 (c 0.3 MeOH).

(b) (IR, 4S) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol ·

After filtration of the IS, the 4R isomers (Example 14a) were combined and evaporated to dryness. The unmodified diamino starting material was separated on a silica gel column using 10% methanol / chloroform. The diamino compound was dissolved in 0.05MK ₂ ^PO 4 P ^{in the ether} 'P ^{H 7} - ⁴ (15ml) and 800 units of adenosine deaminase were added. The solution was incubated for 96 hours at 37 ° C. The TLC showed that there was something unchanged in the product. The solution was heated in boiling water for 3 minutes and treated to remove the denatured protein. An additional 800 adenosine deaminase units were added and the procedure was repeated. The deproteinized solution was evaporated to dryness and the product was crystallized from water. The title compound as a white solid was collected by filtration from water, tt265-270 °.

[alpha] ²⁴ + β1.1 (c 0.3 MeOH).

Example 15 (i) (1-alpha, 4-alpha) -4- (2-Amino-6-hydroxy-9H-purin-9-yl) -2-cyclopentenylacetoxy carbinol

To a suspension of the products of Example 10 (130 mg, 0.50 mmol) and 4-dimethylaminopyridine (5mg, 0.04mmol) in a mixture of acetonitrile (6ml) and triethylamine (0.09ml, 0.66mmol), acetal anhydride (0.06ml, 0.6mmol) was added. The mixture was stirred at room temperature for 3 hours. Methanol (lml) was added to quench the reaction. The solution was concentrated and absorbed on silica gel (1.5g), packed on a column (2.0 x 12cm), eluted with CHCl3-MeOH (20: 1). Product fractions were collected and concentrated to give a white solid. The solid was washed with MeOH-AcOEt; yield, 123mg (85%). Further purification from methanol gave the title compound as needle crystals, mp 237-239 ° C. Anal. (C ^^ H ^^ N ^ O ^) C, H, N. Example 16 (IS, 4R) -4- [2-Amino-9H-purin-9-yl] -2-cyclopentenylcarbinol

A stirred, ice-cooled solution of (1S, 4R) -4- [2-amino-6methoxyamino-9H-purin-9-yl] -2-cyclopentene-methanol (Intermediate 8, Example 12) (1.202g) in tetrahydrofuran (250ml) and water (50ml) was treated with aluminum amalgam (aluminum (1.761g) and 0.5% aqueous solution of macruri chloride), added in small pieces by the Ih time and 47 min. After 35 min. the mixture was allowed to warm to ambient temperature. After 16h 50min aluminum amalgam (from 235mg aluminum) was added for 14min. After a further 4h lOmin the resulting mixture was passed through 'kieselguhr * to remove the insoluble portion. This was washed with tetrahydrofuran: water (5: 1, 300ml). The combined filtrates were evaporated leaving a yellow foam. The foam was chromatographed on silica gel (33.8g, Merck 7734) prepared in chloroform, eluting with chloroform-ethanol mixtures to give several fractions (578mg, 420mg and 40mg). The two larger fractions were separately crystallized from isopropanol. The filtrates were combined with the smallest fraction and subjected to preparative thin-layer chromatography (Merck 5717) and developed three times in 10: 1 chloroform: methanol. The plates were eluted with ethyl acetate and ethyl acetate-ethanol (1: 1) to give a brown solid (45mg). The solid was chromatographed on a silica gel column (2.7g, Merck 7734) prepared in chloroform and eluted with chloroformmethanol-triethylamine mixtures to give a gum (17xng).

After unsuccessful crystallization from isopropanol and treatment with coal in methanol, the aqueous solution of the isolated material was freeze-dried to give the title compound (15mg).

¹ H nmr (DMSO-dJ 1.62 (1H), 2.63 (1H), 2.89 (1H), 3.45

D (2H), 4.73 (1H), 5.48 (1H), 5.91 (1H), 6.14 (1H), 6.50 (2H), 7.98 (1H), 8.57 (1H). Mass spectrum, [MH] ⁺ 232.

Claims (17)

PATENT APPLICATIONS A process for the preparation of compounds of formula (I) X and N / V \ I »· Λ Λ / Z N N (I) HO-CH in which X is hydrogen, NRR ¹ , SR, OR or halogen; Z is hydrogen, OR ² or NRR ¹ ; R, R ¹ and R ² may be the same or different and are selected from hydrogen, C _M alkyl, and aryl, and pharmaceutically acceptable derivatives thereof, characterized in that it comprises (A) reacting a compound of formula (II) (II) ΐ i NH YCH \ ² / \ in which X and Z are defined as in formula (I), or in their protected forms, Y is OH, or a protected form thereof, with a reagent selected from formic acid and its reactive derivatives, and then, if necessary, removing the unwanted groups introduced by said reagent and / or removing any protecting groups present or (B) interconverting the compound of formula (I) or its protected form to another compound of formula (I) by substituting a substituent X with a different substituent X and / or by replacement of substituent Z with another substituent Z, and then, if necessary, removing -33 - any protecting groups present. Process according to claim 1, characterized in that in method (A) the reagent is selected from formic acid, orthoformate, dialkoxylmethyl acetate, dithio formic acid, formamide, s-triazine or formamidine acetate. Process according to Claim 1 or Claim 2, characterized in that in mode (A) the solvent is trialkyl orthoformate, amide, chlorinated hydrocarbon, ether or ntryl. A process according to any one of claims 1 to 3, characterized in that in mode (A) the reaction is carried out at a temperature of -25 ° C to +150 ° C. Process according to claim 1, characterized in that in mode (B), the compound of formula (I) in which X is halogen is converted into a compound of formula (I) in which X is NRR ¹ , OR, SR or H . Process according to any one of claims 1 to 5, characterized in that the compound of formula (I) or a pharmaceutically acceptable salt thereof is obtained. A process according to any one of claims 1 to 6, characterized in that Z in formula (II) is H, OH or NHy A process according to any one of claims 1 to 7, characterized in that Z in formula (II) is an NH ₂ group. A process according to any one of claims 1 to 8, characterized in that X in formula (II) is hydrogen, chlorine, NH ₂ , SH or OH. A process according to any one of claims 1 to 9, characterized in that X in formula (II) is an OH group. A process according to any one of claims 1 to 9, characterized in that X in formula (II) is hydrogen or NH ₂ . A process according to any one of claims 1 to 6, characterized in that the compound of formula (I) is selected from: (1-alpha, 4-alpha) -4- (6-chloro-9H-purin-9-yl) -2-cyclopentenyl carbinol; (1-alpha, 4-alpha) -4- (6-hydroxy-9H-purin-9-yl) -2-cyclopentenyl carbinol; (1-alpha, 4-alpha) -4- (6-amino-9H-purin-9-yl) -2-cyclopentenylcarbinol; (1-alpha, 4-alpha) -4- (6-mercapto-9H-purin-9-yl) -2-cyclopentenyl carbinol; (1-alpha, 4-alpha) -4- (2,6-diamino-9H-purin-9-yl) -2-cyclopentenyl carbinol; (1-alpha, 4-alpha) -4- (2-amino-6-chloro-9H-purin-9-yl) -2-cyclopentenyl carbinol and (1-alpha, 4-alpha) -4- (2- amino-9H-purin-9-yl) -2-cyclopentenyl carbinol. Process according to any one of claims 1 to 6, characterized in that the compound of formula (I) is (1-alpha, 4-alpha) -4- (2-amino-6-hydroxy-9H-purin-9- yl) -2-cyclopentenyl carbinol. Process according to any one of claims 1 to 13, characterized in that the compound of formula (II) is in the form of a racemic mixture. A process according to any one of claims 1 to 13, characterized in that the compound of formula (II) is composed of one of the optical isomers. A process according to any one of claims 1 to 13, characterized in that the compound of formula (II) is composed of the D-isomer. A method according to any one of claims 1 to 4, characterized in that it comprises an additional step for converting a racemic compound of formula (I) or formula (II) into one optical isomer, or the same or different compounds of formula (I) or s formula (II).