Title of Invention

A PROCESS FOR PREPARING A PURINE DERIVATIVE AND A PROCESS FOR THE PRODUCTION OF A COMPOUND

Abstract ABSTRACT IN/PCT/200Q/00450/CHE "A process for preparing a purine derivative and a process for the production of a compound" The present invention relates to a process for preparing a purine derivative of formula (II): wherein R and R' are selected independently from hydrogenC1-12 alkyl; and R1 and R2 are selected independently from hydrogen, hydroxy, halo, C1-12 alkyl- or aryl carbonate, amino, mono- or di-C1-12alkylamino, C1-12 alkyl- or arylamido, C1-12 alkyl-or arylcarbonyl, C1-12 alkyl- or arylcarbamoyl, C1-12 alkyl, C2-n alkenyl, C2-12 alkynyl, aryl, heteroaryl, C1-12 alkoxy, aryloxy, azido, C1-12 alkyl- or arylthio, C1-12 alkyl- or arylsulfonyl, C1-12alkyl- or arylsilyl, and C1-12alkyl- or arylphosphoryl; by subjecting a purine derivative of formula (I): wherein R, R', R1 and R2 are as defined for formula (II) to a rearrangement step in the presence of a palladium (0) dibenzylidene catalyst and a (diphenylphosphino)nC1-6 alkane, wherein n is an integer of from 1-6 and recovering the purine derivative of formula I from the reaction mixture in a known manner.
Full Text

PROCESS FOR THE PRODUCTION OF PURINE DERIVATIVES
The present invention relates to a novel process for the production of N-9 alkylated purine derivatives. In particular the present invention relates to a rearrangement reaction of N-7 alkylated to N-9 alkylated purine derivatives.
Nucleosides and Nucleotides, 15(5), 981 -994 (1996) and WO 95/28402disclose a process for the manufacture of the anti-viral agents 9-(4-acetoxy-3-acetoxymethylbut-l-yl)-2-aminopurine (famciclovir) and 9-(4-hydroxy-3-hydroxymethylbut-l-yl)guanine (penciclovir). According to this process, the 'bromotriester'route, 2-amino-6-chloropurine is reacted with triethyl 3-bromopropane-l,l,l-tricarboxylate in the presence of base to form diethyl 2-[2-(2-amino-6-chloropurin-9-yl)ethyl]-2-carbethoxymalonate. The crude isolate from this alkylation reaction is then treated with sodium methoxide in methanol to form dimethyl 2-[2-(2-amino-6-chloropurin-9-yl)ethyl] malonate. This product is purified by crystallisation and then successively reduced using sodium borohydride and O-acetylated to give 9-(4-acetoxy-3-acetoxymethylbutyl)-2-amino-6-chloropurine. Famciclovir is produced directly from the latter compound by hydrogenation over a supported palladium catalyst; and penciclovir is produced from this compound by acid hydrolysis of the acetoxy groups.
A disadvantage of this route to famciclovir and penciclovir is that the initial alkylation reaction with the bromotriester reagent gives a mixture of the N-9 and N-7 isomers. 2-Amino-6-chloropurine is a fairly expensive starting material, and accordingly the wastage arising from the production of the unwanted N-7 isomer is undesirable.
EP-A-0352953 discloses a process for the production of purine derivatives according to the bromotriester route in which the ratio of N-9 to N-7 products is improved by converting the 2-amino-6-chloropurine to the analogous 6-iodo, 6-benzylthio or 6-(phenacylmethyl)thio compound.
Whilst the process of EP-A-0352953 represents an improvement in the bromotriester process for producing famciclovir, it suffers from the disadvantages that a material quantity of the N-7 isomer still results, and moreover an additional step of converting the 6-chloro substituent to 6-iodo, 6-benzylthio or 6-(phenacylmethyl)thio is required.
Co-pending application GB 9807114.5 discloses a method of making purine derivatives which comprises reacting 2-amino-6-chloropurine with an allyl derivative in

the presence of a palladium(O) catalyst and a suitable ligand.'This reaction effects N-alkylation of the purine, which proceeds with reasonable regioselectivity in favour of the N-9 isomer, however, it is still desirable to optimise the selectivity of the alkylation in favour of the N-9 isomer over the N-7 isomer.
We have now discovered experimental conditions which greatly enhance this selectivity. In particular, we have found a method of procuring the rearrangement of N-7 alkylated purine derivatives to the N-9 alkylated analogues.
According to the invention therefore there is provided a method of rearranging a compound of formula (I):

(I) wherein R and R'are selected independently from hydrogen and C\,\2 alkyl; and R\ and R2 are selected independently from hydrogen, hydroxy, halo, Cj.12 alkyl- or arylcarbonate, amino, mono- or di-Ci_i2 alkylamino, C\.\2 alkyl- or arylamido, Cj.i2 alkyl- or arylcarbonyl, C\.\2 alkyl- or arylcarboxy, Cj.i2 alkyl- or arylcarbamoyl, Cj_i2 alkyl, C2-12 alkenyl, C2-12 alkynyl, aryl, heteroaryl, C\.\2 alkoxy, aryloxy, azido, C\. 12 alkyl-or arylthio, Cj_i2 alkyl- orarylsulfonyl, C\.\2 alkyl-or arylsilyl, Cj.i2 alkyl-or arylphosphoryl, and phosphato; to form a compound of formula (II):
(ID wherein R, R\ R\ and R2 are as as defined for formula (I);

said method comprising treating the compound of formula (I) with a palladium (0) catalyst and a (diphenylphosphino)nCi_6 alkane, wherein n is an integer of from 1-6.
Any of R, R\ R] and R2, when other than H, may be unsubstituted or substituted by one or more groups selected independently from hydroxy, halo, C\,\2 alkyl- or aryl carbonate, amino, mono- or di- Ci_j2 alkylamino, Cj_i2 alkyl- or arylamido, Cj.j2 alkyl- or arylcarbonyl, C\_\2 alkyl- or arylcarboxy, C\.\2 alkyl- or arylcarbamoyl, C\„\i alkyl, Cj_i2 alkenyl, C\„\2 alkynyl, aryl, heteroaryl, Cj.]2 alkoxy, aryloxy, azido, Cj. 12 alkyl- or arylthio, Cj_i2 alkyl-or arylsulfonyl, Cj.i2 alkyl- or arylsilyl, C\.\2 alkyl-or arylphosphoryl, and phosphato.
The palladium (0) catalyst may be a palladium (0) dibenzylidene catalyst. In a preferred embodiment of the invention the catalyst is a tris(dibenzylidene) dipalladium (0) catalyst, e.g. tris(dibenzylidene) dipalladium (0) chloroform.
The palladium (0) catalyst may be formed in situ from a palladium (II) source such as palladium acetate, or may be added to the reaction as another form of palladium (0), e.g. tetrakis(triphenylphosphine) palladium (0).
The (diphenylphosphino)nCi_6 alkane ligand is preferably a bis(diphenylphosphino)Ci_6 alkane such as l,2-bis(diphenylphosphino)ethane or 1,3-bis(diphenylphosphino)propane.
The rearrangement reaction of the invention may be conducted at a temperature in the range of about 40°-120°C, preferably about 60°-100°C, and typically about 80°C The reaction may be conducted for a period of 1 to 24 hours, preferably 1-12 hours, typically about 4 hours.
The rearrangement reaction of the invention may be carried out in an inert solvent. The inert solvent may be selected from dimethylformamide (DMF), diethylformamide, dimethylacetamide and aqueous dimethylformamide. DMF is preferred.
The reaction may be conducted under an inert atmosphere. Any suitable inert gas may be used, but argon is preferred. Preferably the reaction is carried out under a flow of the inert gas.
R\ is preferably halo, typically chloro.
R2 is preferably an amino group. The amino group may be protected throughout using conventional protecting groups such as benzyl, acetyl or a Schiffs base.

R and R7 are preteraDly CH2UR3 ana UH2UK4 respectively, wnerem K3 ana K4 are selected independently from C\,\2 alkyl, aryl, Cj.12 alkylaryl, C\,\o alkylsilyl, arylsilyl and C\.\2 alkylarylsilyl, or R3 and R4 are joined together to form a cyclic acetal orketal.
Thus the side-chain on N-7 of formula (I) is preferably a 4-alkoxy-3-alkoxymethyl but-2-enyl group of formula (III):
(HI)
R3 and R4 may be selected independently from benzyl and C]_j2 alkyldiphenylsilyl, e.g. t-butyldiphenylsilyl. Preferably however, R3 and R4 are linked to form a six membered cyclic acetal or ketal of formula (IV):
(IV) wherein R5 and R$ are selected independently from H, C]_i2 alkyl, and aryl.
Preferably R5 and Rg are both Cj-i2 alkyl, more preferably R5 and R$ are both methyl.
Thus, in one embodiment of the invention, the rearrangement of the compound of formula (I) to the compound of formula (II) proceeds as follows:


The compound of formula (I) may be introduced as such to the reaction mixture. Alternatively, the compound of formula (I) may be formed in situ by the reaction of a compound of formula (V):
(V) wherein Rj and R2 are as defined for formula (I), with a compound of formula (VI):

(VI) wherein Y is a leaving group and R and R' are as defined for formula (I), in the presence of the dipalladium (0) catalyst and (diphenylphosphino)nCi_6 alkane.
Preferably, the reaction between the compound of formula (V) and the compound of formula (VI) is conducted in the presence of a base. The base may be selected from caesium carbonate, sodium carbonate, potassium carbonate, lithium carbonate, cesium fluoride, lithium hydride, sodium hydride, sodium hydroxide, triethylamine, diazabicyclo [5.4.0]undec-7-ene and 1,1,3,3-tetramethylguanidine. Preferably however the base is caesium carbonate.

Various of the compounds of formula (VI) are novel, thus according to a further aspect of the invention there is provided a compound of formula (VI):
(VI)
wherein Y is a leaving group and R3 and R4 are are joined together to form a cyclic acetal or ketal.
A preferred group of compounds of formula (VI) are those of formula (VII):

(VII) wherein Y is a leaving group and R5 and Rg are selected independently from H, C\.\2 alkyl and aryl. Preferably R5 and Rg are both C\.\2 alkyl, more preferably R5 and R6 are both methyl.
A particular compound of formula (VI) that may be mentioned is methyl 2,2-dimethyl-5-ethenyl-1,3-dioxane-5-carbonate.
The compounds of formula (VI) may be prepared by reacting a compound of formula (VIII):
(VIII)
wherein R and R' are as defined for formula (I), with a vinyl carbanion and thereafter converting the resulting alkoxide to the leaving group Y.
The vinyl carbanion may be a Grignard reagent such as vinylmagnesium bromide.

The nucleophilic addition of the vinyl carbanion to the compound of formula (Vin) may be carried out in an inert solvent such as tetrahydrofuran, at a temperature of less than about -60°C, preferably about -78°C.
The leaving group Y may be selected from the group consisting of Cj.g alkyl- or aryl carbonates, e.g. methyl carbonate or phenyl carbonate; C\„$ acyloxy e.g. acetate or trifluoroacetate; or C].g alkylphosphates, e.g. diethylphosphate. A C\_$ alkyl carbonate is preferred however, because it gives rise to volatile side products when reacted with the compound of formula (V). The leaving group may be introduced by, for example, quenching the reaction between the compound of formula (VIII) and vinyl carbanion with a C]_6 alkyl chloroformate, e.g. methyl chloroformate, if desired. The 5-vinyl-5-hydroxy intermediate formed by reaction of the vinyl carbanion with the compound of formula (VIII) may be isolated before ihe leaving group Y is introduced. The compound of formula (VI) may be isolated and purified by known methods. Alternatively, the compound of (VI) may be used as a crude oil without purification.
In another aspect of the invention there is provided a process for the production of a compound of formula (IX):
(IX)
wherein X is H or OH; and R7 and Rg are independently selected from H and R9CO wherein R9 is phenyl, Cj.12 alkyl or phosphoryl; which process comprises rearranging a compound of formula (I) in which R\ and R2 are as defined for formula (I), and R and R' are respectively CH2OR3 and CH2OR4 as defined for formula (III), to form a compound of formula (II) according to the process of the invention defined above; hydrogenating the compound of formula (II); converting -OR3 and -OR4 to form two hydroxy groups; and thereafter if and as necessary:

(i) converting one or both of the hydroxy groups on the resulting 4-hydroxy-3-hydroxymethylbutyl to form compounds where R7 and Rg represent R9CO; and/or
(ii) converting Rj to X and R2 to NH2.
Preferably R7 and Rg are both hydrogen or acetyl. When X is H and R7 and Rg are both acetyl the compound of formula (IX) is famciclovir. When X is OH and R7 and Rg are both H, the compound of formula (IX) is penciclovir.
Hydrogenation of the ethylidene moiety may be effected by hydrogenation of the compound of formula (II) in the presence of a catalyst, preferably a palladium catalyst, such as palladium on charcoal. Other suitable catalysts are Pd/CaC03 and Pd(OH2)/C. The hydrogenation may be carried out in a solvent selected from the group consisting of alkyl esters e.g. ethyl acetate, tetrahydrofuran, and Cj.g alkylalcohols e.g. methanol or ethanol.
Optionally a base is included in the reaction mixture. The base may be selected from triethylamine, sodium acetate, potassium hydroxide, aqueous sodium hydroxide and basic alumina. Alternatively, a basic ion exchange resin may be employed. Hydrogenation may be carried out at an elevated temperature and pressure or, alternatively, at room temperature and atmospheric pressure. As mentioned above, Rj is preferably halo such as chloro. In accordance with an important aspect of the invention, hydrogenation of the compound of formula (II) in the presence of a base reduces both the chloro moiety (to H) at the 6-position on the purine ring and also the double bond. This one step reduction of the 6-chloro and ethylidene groups represents a particularly advantageous synthetic route to famciclovir. The reduced product may be isolated if required. In the absence of base, only the double bond is reduced. Subsequent hydrolysis of the 6-chloro group and -OR3 and -OR4 then affords penciclovir. Therefore, the choice of whether or not to use a base allows the synthesis of either famciclovir or penciclovir.
-OR3 and -OR4 may be converted to -OH by any suitable method known to those skilled in the art such as those described in EP 141927. Cyclic acetals or ketals are preferably hydrolysed using tetrahydrofuran/methanol and hydrochloric acid. Where R\ and R2 are benzyl, then hydrogenation may be used.
In a particularly preferred embodiment of this aspect of the invention, the two hydroxy groups of the 4-hydroxy-3-hydroxymethylbut-l-yl group are acylated. Any

convenient acylation method known to those skilled in the art may be used, such as those described in EP 182024, preferably acetic anhydride is employed.
Unless otherwise stated, any of the alkyl groups mentioned above may comprise 1-12 carbon atoms, preferably 1-6 carbon atoms. Alkyl groups may be straight or branched chain or cyclic. Cyclic alkyl groups preferably comprise 3-8 carbon atoms. Any alkyl groups may be substituted by one or more fluoro atoms. Alkenyl and alkynyl groups should be construed accordingly.
Any of the aryl groups mentioned above preferably comprise 5-10 carbon atoms and may be mono- or bicyclic. Suitable aryl groups included phenyl and naphthyl, preferably phenyl.
Any of the heteroaryl groups mentioned above preferably comprise 5-10 carbon atoms, may be mono- or bicyclic and contain 1, 2 or 3 heteroatoms selected from oxygen, nitrogen and sulphur.
All publications, including but not limited to patents and patent applications, cited in this specification are herein incorporated by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein as though fully set forth.
There follows a description by way of example only of embodiments of the present invention.
Example 1
Preparation of methvl 2,2-dimethvl-5-ethenvl-l. 3-dioxane-5-carbonate
2,2-Dimethyl-l,3-dioxan-5-one (38.0g) in tetrahydrofuran (250ml) was added dropwise to a 1M solution of vinylmagnesium bromide in tetrahydrofuran (700ml) under argon maintaining a temperature of less than -60°C. The reaction mixture was cooled to -78°C and stirred at this temperature for 30 min. Methyl chloroformate (75ml) was added dropwise and the resulting mixture stirred at -78°C for 15 min before being allowed to warm to room temperature. The solvent was removed by evaporation under reduced pressure. Ethyl acetate (2x500ml) was added to the residue and the solvent removed by distillation after each addition. The residue was stirred in ethyl acetate/hexane 40:60 and the resulting mixture passed through a short silica column. The column was washed with further ethyl acetate/hexane 40:60 (2x1.0L) and the combined fractions concentrated to

give an oil. The crude oil was purified by silica column chromatography (eluent hexane 'ethyl acetate 90:10 increasing to hexane/ethyl acetate 85:15) to give the title compound is a pale yellow oil (46g, 73% yield).
Hnmr (CDC13): 5 6.0 (dd, 1H, CH); 5.3 (m, 2H, CH2); 4.05 (abq, 4H, 2xCH2); 3.75 (s, 5H, OCH3); 1.45 (s, 3H, CH3); 1.4 (s, 3H, CH3)
Example 2
Example 1 was repeated except that, as an alternative to purification by column ;hromatography, the methyl 2,2-dimethyl-5-ethenyl-l,3-dioxane-5-carbonate was purified by distillation at 78°C and 0.6mmHg.
Example 3
Example 1 was repeated, except that the reaction mixture was poured into 1M potassium dihydro-orthophosphate then extracted into diethyl ether and purified by :olumn chromatography.
Example 4
Example 1 was repeated, except that the reaction mixture was concentrated and the residue slurried in diethyl ether and saturated brine. The ether layer was concentrated, and the residue purified by column chromatography.
Example 5
Preparation of 5-f2-(2-amino-6-chloropurin-9-vl)lethvlidene-2.2-dimethvl-l .3-
dioxane
2-Amino-6-chloropurine and methyl 2,2-dimethyl-5-ethenyl-l,3-dioxane-5-carbonate were suspended in DMF and degassed under high vacuum for 15 min. To the reaction was added cesium carbonate, l,2-bis(diphenyl-phosphino)ethane [DIPHOS] and Pd2dba3.CHCl3 as a palladium (0) source. The reaction was degassed a second time then stirred at 60°C overnight under a flow of argon. The reaction was worked up by evaporating the solvent and crystallising the residue from methanol to give the title compound (61% yield). lHnmr (DMSO-Jtf): 8 8.1 (s, 1H, CH); 6.9 (s, 2H, NH2); 5.5 (t, 1H, CH);

4.6 (d, 2H, CH2); 4.5 (s, 2H, CH2); 4.2 (s, 2H, CH2); 1.3 (s, 6H, 2xCH3) m.p. 157-159°C
Example 6
Preparation of 5-r2-(2-aminopurin-9-vl)ethvl1-2,2-dimethvI-1.3-dioxane
A mixture of 5-[2-(2-amino-6-chloropurin-9-yl)]ethyIidene-2,2-dimethyl-l ,3-dioxane (0.45g), 5% palladium on carbon (0.225g) and triethylamine (0.22ml) in ethyl acetate (22.5ml) was hydrogenated at 50°C for 18 hours at 50 p.s.i. The catalyst was removed by filtration and the filter washed with ethyl acetate. The combined filtrate and wash were concentrated under reduced pressure to give a gum which was purified by silica gel chromatography (eluted with dichloromethane/methanol 99:1 increasing to 97:3) to give the title compound (300mg, 74% yield). 'Hnrnr (DMSO-d6): 8 8.6 (s, 1H, CH); 8.1 (s, 1H, CH); 6.5 (s, 2H, NH2), 4.1 (t, 2H, CH2);
3.8-3.5 (m, 4H, 2xCH2); 1.73 (q, 2H, CH2); 1.6 (m, 1H, CH); 1.3 (s, 3H, CH3); 1.25 (s, 3H, CH3)
Example 7
Preparation of 5"r2-(2-amino*6-chloropurin-9*vl)ethvll-2.2-dimethvI-l,3-dioxane
5% Palladium on carbon (1.5g) in tetrahydrofuran (40ml) was prehydrogenated for 30 min at 50 p.s.i. 2,2-Dimethyl-5-[2-(2"amino-6-chloropurin-9-yl)]ethylidene-l,3-dioxane (3.0g) in tetrahydrofuran (80ml) was added and washed in with tetrahydrofuran (30ml). The mixture was hydrogentated overnight at 50 p.s.i. with stirring. The catalyst was removed by filtration to give a colourless solution. The solvent was removed under reduced pressure and the residue recrystallised from IPA to give the title compound (1.92g, 62.2% yield).
'Hnrnr (DMSO-d6): 8 8.18 (s, 1H, CH); 6.91 (s, 2H, NH2); 4.08 (t, 2H, CH2); 3.8 (dd, 2H, CH2); 3.5 (dd, 2H, CH2); 1.75 (m, 2H, CH2); 1.59 (m, 1H, CH); 1.33 (s, 3H> CH3); 1.27 (s, 3H, CH3) Analysis: Found C: 50.14; H: 5.88; N: 22.34%; Required: C: 50.08; H: 5.82; N: 22.46%
5-[2-(2-Amino-6-chloropurin-9-yl)ethyl]-2,2-dimethyl-l,3-dioxane can be converted to penciclovir using techniques known in the art such as those described in EP 141927.

Example 8
Preparation of 2"amino-9-(4"hvdroxv*3-hvdroxvmethvlbut-l-vl)Durine
hydrochloride
To a stirred solution of 2,2-dimethyl-5-[2«(2-aminopurin-9-yl)ethyI]-l,3"dioxane (lg) in a mixture of tetrahydrofuran (20ml) and methanol (6ml) at room temperature was added concentrated hydrochloric acid (0.32ml). The resulting mixture was stirred for 2 hours during which time a solid crystallised. The solid was collected by filtration, washed with tetrahydrofuran (2ml) and dried under a flow of air to give the desired product as the hydrochloride salt (800mg, 81% yield).
'Hnmr (DMSO-afc/D20): 5 8>9 (S) 1H, CH); 8.6 (s, 1H, CH); 4.2 (t, 2H, CH2); 3.5-3.3 (m, 4H, 2xCH2); 1.8 (q, 2H, CH2); 1.5 (m, 1H, CH) m.p. 174-176°C
Example 9
Preparation of 9-(4-acetoxv-3-acetoxvmethvlbut-l»vl)-2-aminopurine (famciclovir)
To a stirred suspension of 2-amino-9«(4-hydroxy-3-hydroxymethylbut-l-yl)purine hydrochloride (0.79g), 4-dimethylaminopyridine (16mg) and triethylamine (1.4ml) in dichloromethane (16ml) at room temperature was added acetic anhydride (0.57ml). The resulting mixture was stirred at ambient temperature for 2.25 hours. Methanol (4ml) was added and the solution stirred for 30 min before being evaporated to dryness. Water (20ml) was added and the aqueous solution extracted with dichloromethane (3x20ml). The combined extracts were concentrated to give an oil. This oil was dissolved in 2-propanol (5ml), the solvent evaporated and the residue recrystallised from 2-propanol (5ml). The product was collected by filtration, washed with 2-propanol (3ml) and dried to give the title compound (654mg, 70%).
'Hnmr (DMSO-6): 5 8.6 (s, 1H, CH); 8.1 (s, 1H, CH); 6.5 (s, 2H, NH2); 4.1 (t, 2H, CH2); 4.0 (d, 4H, 2xCH2); 2.0 (s, 6H, 2xCH3); 1.9 (m, 3H, CH and CH2)
Example 10
Rearrangement of 5-r2-(2-amino*6-chloropurin-7"Vl)1ethvlidene>2,2-dimethvM>3-
dioxane

5-[2-(2-Amino-6-chloropurin-7-yI)]ethylidene-2,2-dimethyl-1,3-dioxane was suspended in DMF and degassed under high vacuum for 15 min. To the mixture was added the Pd2dba3.CHCl3 and bis(diphenylphosphino)ethane (DIPHOS). The reaction was degassed for a second time then stirred at 80°C, overnight, under a flow of argon. The solution yield of 5-[2-(2-aminopurin-9-yl)ethyl]-2,2-dimethyl-l,3-dioxane was 60%.


CLAIMS
1. A method of rearranging a compound of formula (I):
(I)
wherein R and R' are selected independently from hydrogen and C1-12 alkyl; and R1 and R2 are selected independently from hydrogen, hydroxy, halo, C1-13alkyl-or aryl carbonate, amino, mono- or di-C1-12 alkylamino, C1-12 alkyl- or arylamido, C1-12 alkyl- or arylcarbonyl, C1-12 alkyl- or arylcarboxy, C1-12 alkyl- or arylcarbamoyl, C1-12 alkyl, C2-12 alkenyl, C2-12 alkynyl, aryl, heteroaryl, C1-12alkoxy, aryloxy, azido, C1.12 alkyl- or arylthio, C1-12 alkyl- or arylsulfonyl, C1-12alkyl- or arylsilyl, C1-12 alkyl- or arylphosphoryl, and phosphato; to form a compound of formula (II):

wherein R, R\ R1and R2 are as defined for formula (I);

said method comprising treating the compound of formula (I) with a palladium (0) catalyst and a (diphenylphosphino)nC1-6 alkane, wherein n is an integer of from 1-6.
2. A method as claimed in claim 1, wherein the catalyst is a palladium (0) dibenzylidene catalyst.
3. A method as claimed in claim 1 or 2, wherein the (diphenylphosphino)nC1-6 alkane is a bis(diphenylphosphino)C1-6 alkane.
4. A method as claimed in any one of the preceding claims, wherein the rearrangement reaction is conducted at a temperature in the range of about 40°-
120°C.
5. A method as claimed in any one of the preceding claims, wherein the rearrangement is carried out in an inert solvent under an inert atmosphere.
6. A method as claimed in any one of the preceding claims, wherein R\ is chloro and R2 is an amino group.
7. A method as claimed in any one of the preceding claims, wherein R and R' are CH2OR3 and CH2OR4 respectively, wherein R3 and R4 are selected independently from C1-12 alkyl, aryl, C1-12 alkylaryl, C1-12alkylsilyl, arylsilyl and C1-12 alkylarylsilyl, or R3 and R4 are joined together to form a cyclic acetal or ketal.
8. A method as claimed in claim 7, wherein R3 and R4 are linked to form a six membered cyclic acetal or ketal of formula (IV):

(IV) wherein R5 and Rg are selected independently from H, C\-\2 alkyl, and aryl.
9. A method as claimed in any preceding claim, wherein the compound of
formula (I) is formed in situ by the reaction of a compound of formula (V):

(V) wherein R1 and R2 are as defined in claim 1, with a compound of formula (VI):
(VI)
wherein Y is a leaving group and R and R' are as defined in claim 1, in the presence of a palladium (0) catalyst and a (diphenylphosphino)nC1-6alkane.
10. A process for the production of a compound of formula (IX):

(IX)
wherein X is H or OH and R7 and Rg are independently selected from H and R9CO wherein R9 is phenyl, C1-12 a'kyl or phosphoryl; which process comprises rearranging a compound of formula (I) in which R1 and R2 are as defined in claim 1, and R and R' are respectively CH2OR3 and CH2OR4 as defined in claim 7, according to the process of any one of the preceding claims to form a compound of formula (II); hydrogenating the compound of formula (II); converting -OR3 and -OR4 to form two hydroxy groups; and thereafter if and as necessary:
(i) converting one or both of the hydroxy groups on the resulting 4-hydroxy-3-hydroxymethylbutyl to form compounds where R7 and Rg represent R9CO; and/or (ii) converting R\ to X and R2 to NH2.
11. A process as claimed in claim 10, wherein the compound of formula (DC) is 9-(4-acetoxy-3-acetoxymethylbut-l-yl)-2-aminopurine (famciclovir), or 9-(4-hydroxy-3-hydroxymethylbut-l-yl)guanine (penciclovir).

12.A method of rearranging a compound of formula (I) substantially as hereinbefore described.
13.A process for the production of a compound of formula (IX) substantially as hereinbefore described.


Documents:

in-pct-2000-450-che-abstract.pdf

in-pct-2000-450-che-assignment.pdf

in-pct-2000-450-che-claims duplicate.pdf

in-pct-2000-450-che-claims original.pdf

in-pct-2000-450-che-correspondance others.pdf

in-pct-2000-450-che-correspondance po.pdf

in-pct-2000-450-che-description complete duplicate.pdf

in-pct-2000-450-che-description complete original.pdf

in-pct-2000-450-che-form 1.pdf

in-pct-2000-450-che-form 26.pdf

in-pct-2000-450-che-form 3.pdf

in-pct-2000-450-che-form 5.pdf

in-pct-2000-450-che-other documents.pdf

in-pct-2000-450-che-pct.pdf


Patent Number 207305
Indian Patent Application Number IN/PCT/2000/450/CHE
PG Journal Number 26/2007
Publication Date 29-Jun-2007
Grant Date 04-Jun-2007
Date of Filing 27-Sep-2000
Name of Patentee M/S. NOVARTIS INTERNATIONAL PHARMACEUTICAL LTD
Applicant Address 48 CHURCH STREET,HAMILTON, HM 12.
Inventors:
# Inventor's Name Inventor's Address
1 GEEN, Graham, Richard SmithKline Beecham Pharmaceuticals New Frontiers Science Park South Third Avenue Harlow Essex CM19 5AW.
PCT International Classification Number C 07D473/32
PCT International Application Number PCT/EP1999/002309
PCT International Filing date 1999-03-30
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 9807116.0 1998-04-02 Russia