FI64160C - NYTT FOERFARANDE FOER FRAMSTAELLNING AV ANTIVIRALA SUBSTITUERADE PURINFOERENINGAR - Google Patents

Description

M <ii) * uu, lutusjul, ca, su 6 ^ 60 Ή2Άφ l J '' utlAggningsskrift '^ v (51) Kv.lk?/tefcCL3 o 0? D 473/02 FINLAND — FINLAND (21) λ * «**» - 7725U8 (22) Hatomfeplivt -— AmBkninfrfag 26.08-77 ^ ^ (23) AlkupiWi — GiMgbatadag 26.08.77 (41) Tulhit ptlklMlul— Bdvtt off «ntkj og qm

Patent · and register controller / 44) NihtMloip.M. j. month date

Patent * och ragitterstyralMn AiwtUcan ud ** d och utUkriften pubikond, u · '' · 1 '(32) (33) (31) Privilege claimed — Begird prlorltsc 2'7.08.76 28.02.77 USA (UO) 718109, 7731 19 \ 7l) Tne Wellcome Foundation Limited, 103-193 Euston Road, London NWI, Englcin ti -England (GB) (72) Howard John Schaeffer, Raleigh, North Carolina, USA (US) (7M Oy Kolster Ab (9 * 0 New method for the preparation of substituted antiviral compounds of viruses - Nytt förfarande för framställning av antivirala substituerade purinföreningar

The invention relates to a process for the preparation of compounds of formula (I)

R

Λ / \

OF

y (I)

N N

H ~ N I

1 CH2OCH2CH2OH

wherein R is amino or hydroxy.

9- (2-hydroxyethoxymethyl) derivatives of purines have antiviral activity against various classes of DNA and RNA viruses both in vitro and in vivo. In particular, these compounds are active as antiviral agents against adenovirus such as adenovirus 5 and rhinovirus. They are particularly active as antiviral agents in mammals against vaccinia 2 64160 and herpesviruses, including simplex, zoster and varicella, which viruses cause diseases such as rubella-like cornea in rabbits and rubella-like encephalitis in mice.

Examples of 9- (2-hydroxyethoxymethyl) derivatives of purines with particularly good antiviral activity are 9- (2-hydroxyethoxymethyl) guanine and 2-amino-9- (2-hydroxyethoxymethyl) adenine.

Numerous methods are known for the preparation of 9- (2-hydroxyethoxymethyl) derivatives of purines; they can be prepared, for example, by removing the protecting group at the 2-position of the side chain. Alternatively, they can be formed by conversion to a different substituent in the 2- and / or 6-substituent purine ring (see GB application 38278/74).

Applicant's previous application (FI application 752 465) describes various methods for preparing the above-mentioned compounds. In one of these methods, namely method (a) described in on the explanatory page 4 of the application, the protecting group Y is removed from the terminal position of the side chain in the 9-position. It is mentioned on page 5 that acyl groups, such as acetyl or benzoyl groups, which can be removed by basic hydrolysis, can be used as a protecting group.

The second method is mentioned in the applicant's previous application on page 5 (e), in which case the protecting groups 1 2 in the 6- and 2-positions are removed from the R and R groups. In connection with this method, it is mentioned at the top of page 8 that trimethyl groups are used as protecting groups, and later in the same paragraph it has been suggested that these groups can be removed by solvolysis using alcoholic or aqueous ammonia, or by alcoholysis.

Thus, it is clear from the applicant's previous application that different protecting groups and different conditions for deprotection are selected based on whether the 2- and / or 6-position protecting groups or the 9-side chain terminal protecting groups were not considered possible due to the simultaneous removal of 2 -, 6- and 9-position protecting groups in one step under the same reaction conditions. The present invention, on the other hand, is based on the surprising finding that the acyl protecting groups in the 2-, 6- and 9-positions can be removed in one step by basic hydrolysis.

The use of acyl groups to protect amino and hydroxy groups in the preparation of 9-substituted derivatives of purines is described in FI patent applications 2408/69 and 3263/71.

li 64160 FI patent application 2408/69, however, concerns compounds which differ significantly from the compounds of the present application. Thus, in the compounds of the previous application, the 9-position of the purine backbone is substituted by a carboxyalkylene group, while in the compounds of the latter application, the 9-position is substituted by a hydroxyethoxymethoxy group, the group having a greater tendency to cleave at the oxygen atom adjacent to the methylene group. In the compounds according to said FI application, such a possibility does not exist in the 9-side chain.

FI patent application 3263/71 does not mention any method by which the protecting groups can be removed both from the 2- and 6-positions of the purine backbone and from the terminal position of the 9-side chain. It should be noted that in method (c) of claim 1 of said application, the groups in the 2- and 6-positions of the purine backbone are removed, but the Z-protecting group of the 9-side chain remains intact and is subsequently removed under various reaction conditions. Thus, it does not appear from that application that the protecting groups at three different sites on the molecule could be removed under similar reaction conditions. The compounds of said application differ from the compounds of the present application in that they contain a sugar group at the 9-position of the purine backbone.

It has now been found that certain 9- (2-hydroxyethoxymethyl) derivatives of purines can be prepared in a new and preferred synthetic manner. Thus, in accordance with the present invention, there is provided a process for the preparation of compounds of formula (I):

R

Λ.Χ.)

H N I

2 CH2OCH2CH2OH

wherein R is amino or hydroxy, wherein in the presence of a base a compound of formula (II) is hydrolysed: R 1 ι'Χ y

o O

1 It 2 I II p

X -C-NR CH 2 OCH 2 CH 2 -O-C-X

4,64160 1,212 wherein R is hydroxy or -NR .CX. and X and X are similar

O

2 or different and each is an alkyl or phenyl group and R is hydrogen or -CX, provided that when R is hydroxy, R is hydrogen.

O

1 2

When X and X are alkyl groups, they preferably have 1 to 4 carbon atoms, most preferably they are similar and are a methyl group.

The base used in the hydrolysis may be an aqueous or alcoholic, primary or secondary aliphatic amine, an alkoxide in an alcohol or an aqueous or alcoholic hydroxide, for example sodium alkoxide or hydroxide, with a preferred base being an aqueous primary aliphatic amine, e.g. aqueous methylamine. Depending on the base used, the hydrolysis can be performed from room temperature to steam bath temperature. In general, the lower the reaction temperature, the longer the reaction time, but the fewer side reactions.

1 2 1.2

An intermediate of formula (II) wherein R is -NR CX and R is

O

-Cx 1 can be completely hydrolyzed in one step using, for example, aqueous methylamine. Alternatively and more preferably, the intermediate of formula (II) is deacylated in two steps; in the first step, one -C-X4 group is removed from the purine ring

II

O

2- and 6-positions by slight hydrolysis at room temperature using, for example, butylamine in a lower alcohol. The second step of the hydrolysis, removal of the remaining -C-X groups, is performed at 0 using a strong base such as aqueous methylamine.

The intermediates of formula (II) are new. These compounds can be prepared by reacting guanine or 2-aminoadenine in which the 2- and 9- or 2-, 6- and 9-positions, respectively, are acylated with a diester or 2-oxa-1,4-butanediol with a catalytic amount of a strong acid, such as sulfuric acid, sulfonic acids such as p-toluenesulfonic, methanesulfonic or trifluoromethanesulfonic acid, sulfamic acid, bis- (p-nitrophenyl) phosphate or polyphosphoric acid.

The acylated purine, in turn, can be prepared by reacting the appropriate purine with an acid anhydride, such as acetic anhydride, or another acylating agent, e.g., an acid halide.

II

5 6 416 G

The diester of 2-oxa-1,4-butanediol is prepared by reacting a Dick solane with an acid anhydride in the presence of a catalytic amount of a strong acid such as one of the acids listed above.

The present process is characterized by good yields, in Examples 1 to 8, the overall yields are 91.8%, 89.6%, 89.9% and 96%.

The invention will now be illustrated by reference to the following examples.

Example 1-9- (2-Hydroxyethoxymethyl) guanine

To a mixture of acetic anhydride (102 g), acetic acid (15 g) and p-toluenesulfonic acid (5.0 g) cooled to 10 ° C was added dioxolane (70 g) with stirring and cooling so that the temperature of the vessels never exceeded 40 ° C. C. The mixture was then cooled to room temperature and toluene (300 ml) and di-acetylguanine (50 g) were added. The reaction mixture was then heated to reflux with stirring for 16 hours. It was then cooled to room temperature, chloroform (50 ml) was added, and the solid residue was removed by filtration. The press cake was washed thoroughly with chloroform and dried. To the dried press cake was added 40% aqueous methylamine (350 ml), and the mixture was heated under reflux with stirring for 40 minutes, cooled and filtered. The filtrate was evaporated under reduced pressure to a thick mixture. The mixture was cooled, filtered and the press cake was washed with ethanol and dried to give 9- (2-hydroxyethoxymethyl) -guanine (27 g, more than 90% pure), m.p. 255-257 ° C. Yield = 56%.

Example 2-9- (2-hydroxyethoxymethyl) guanine

A mixture of diacetylguanine (50 g), 2-oxa-1,4-butanediol diacetate (59.8 g) and p-toluenesulfonic acid (1.2 g) in toluene (350 ml) was heated under reflux with stirring for 16 hours. The mixture was cooled to room temperature, filtered and the press cake was washed thoroughly with toluene. The press cake was dried and 40% aqueous methylamine (350 ml) was added. The mixture was heated to reflux with stirring for 40 minutes, cooled to room temperature and filtered. The filtrate was evaporated under reduced pressure to give a thick mixture. Ethanol (200 ml) was added to the mixture, which was then cooled, filtered, washed with ethanol and dried to give 9- (2-hydroxyethoxymethyl) guanine (36 g, more than 90% pure). Yield = 75%.

6,641 60

Example 3 - 2-Acetamido-9- (2-acetyloxyethoxymethyl) -hypoxanthine

A mixture of diacetylguanine (1.0 g), 2-oxa-1,4-butanediol diacetate (0.82 g) and p-toluenesulfonic acid (23 mg) in mineral oil (4 g) was heated at 115 ° C with stirring under reduced pressure. overnight. The mineral oil was decanted off. The residue was triturated with chloroform and then extracted with boiling methanol. The methanol extract was concentrated to 50 mL, cooled and filtered. The filtrate was evaporated to dryness to give a solid residue (0.43 g). The solid was purified by column chromatography (silica gel 10 g in chloroform: eluted with 1: 1 chloroform: acetone) followed by recrystallization from ethanol to give 2-acetamido-9- (2-acetyloxyethoxymethyl) hypoxanthine (0.14 g), m.p. 202.5 to 204.5 ° C.

Example 4 - 2-Amino-9- (2-hydroxyethoxymethyl) adenine To a 5 liter flask equipped with a stirrer and reflux condenser (CaCl 2 drying tube) and containing 2-formamidoadenine (89.0 g) was added acetic anhydride ( 4 1). The mixture was refluxed for 60 hours. At the end of this time, the excess anhydride was removed by distillation at atmospheric pressure until about 3.5 L of distillate was obtained. Distillation was continued under reduced pressure to remove residual anhydride. The dark brown residue turned to a viscous gummy mass on cooling to room temperature and then dissolved in dichloromethane, filtered to remove suspended solids and the solvent removed in vacuo to give 211.0 g (> 100%) of 2,6-bis- (diacetylamino-9-acetylpurine). The determined yield was 96.7% based on nmr, the difference being acetic anhydride, (b) Pentaacetylpurine (174 g) was combined with 1,4-diacetoxy-2-oxabutane (126.8 g) in a flask equipped with an air stirrer and a drying tube. This mixture was then placed in an oil bath at 130 ° C and stirred for a few minutes to homogenize the mixture The acid catalyst paratoluenesulfonic acid (2.74 g) was added in one portion and heating was continued in vacuo for 4 hours at which time quantitative conversion to product was observed.

The reaction mixture was then cooled to room temperature and stored under dry nitrogen.

(c) The melt (208.5 g) was dissolved in ethanol (5 ml / g) at room temperature and transferred to a flask equipped with a dropping funnel, stirrer and thermometer. Then n-butylamine li 7 64160 (140.4 g) was added dropwise over two hours and the exothermic reaction was controlled using a water bath. The maximum temperature that the reaction was allowed to reach was only 30 ° C. The product began to separate from the reaction mixture as the addition continued. After the addition was complete, the mixture was stirred at room temperature for 3 hours and then placed in a cold room overnight. The product was removed by filtration to give a dough-like mass which was mixed with acetone (1 x 500 ml) and filtered again. This was dried in vacuo at 65 ° C for 3 hours and then at room temperature overnight to give 154.2 g (91.7%) of a light brown solid. The product was purified by dissolving it in hot dimethylformamide (10 ml / g) at 100-110 ° C to give a cloudy brown solution. After cooling overnight at 5 ° C, the product was removed by filtration, washed with acetone (1 x 250 mL) and air dried to give 121.7 g (78.8%) of 2,6-diacetamido-9- (2 -asetoksietoksimetyyli) purine.

(d) To a stirred solution of aqueous methylamine (608.5 ml of a 40% solution) was added 2,6-diacetamido-9- (2-acetoxyethoxymethyl) purine (121.7 g) for 5 minutes. The addition was followed by a slight rise in temperature which raised the temperature of the mixture to 35 ° C and all solids dissolved in a few minutes. After stirring for 2.5 hours, tls of the mixture indicated the reaction was complete.

The mixture was then concentrated in vacuo with a water bath at 45-50 ° C to give a thick mass of brown crystals. This was then stirred with acetone (545 mL, 7 mL / g) for 15 minutes to remove N-methylacetamide and vacuum filtered. The cake was rinsed with acetone (1 x 200 mL) and air dried to give 74.7 g (96.0%) of coarse hydrated 2-amino-9- (2-hydroxyethoxymethyl) adenine as light brown crystals. These were dried under vacuum at 80 ° C for 18 hours to give 69.3 g (89.0%) of dry product.

Example 5 2-Acetamido-9- (2-acetyloxyethoxymethyl) hypoxanthine (6.19 g) was suspended in 1N sodium hydroxide solution (40 ml), and the suspension was refluxed for one hour. The mixture was cooled and neutralized with 6N hydrochloric acid, and the product was filtered off. The solid was washed with ice water (10 mL) and acetone (15 mL) and dried in vacuo overnight. 4.13 g of (91.8 ') 9- (2-hydroxyethoxymethyl) guanine were obtained, m.p. 255-257 ° C.

8,641 60

Example 6 2-Acetamido-9- (2-acetyloxyethoxymethyl) hypoxanthine (6.19 g) was suspended in a solution of sodium methylate (3.24 g) in methanol (40 ml). The mixture was refluxed for one hour and then allowed to cool. Glacial acetic acid (3.96 g) was added to the mixture, and it was poured into water (40 ml). The mixture was cooled to 0 ° C and the precipitate formed was filtered off, washed with cold water (15 ml) and acetone (15 ml) and dried in vacuo to give 4.03 g (89.6%) of 9- (2-hydroxyethoxymethyl) guanine, m.p. 255-257 ° C.

Example 7.

2-Acetamido-9- (2-acetyloxyethoxymethyl) hypoxanthine (6.19 g) was added to a solution of potassium hydroxide (3.96 g) in ethanol (40 ml), and the mixture was refluxed for one hour. The mixture was allowed to cool, after which glacial acetic acid (3.96 g) was added. The mixture was poured into water (40 ml), and 50 ml of water was added. The pH was adjusted to 7.0 with aqueous sodium hydroxide solution, and the mixture was cooled with ice water and filtered. The solid was washed with cold water (20 ml) and acetone (20 ml) and dried in vacuo to give 4.0 g (88.9%) of 9- (2-hydroxyethoxymethyl) guanine, m.p. 255-257 ° C.

Example 8 2-Acetamido-9- (2-acetyloxyethoxymethyl) hypoxanthine (6.19 g) was suspended in triethylamine (5 g) and water (40 ml), and the mixture was refluxed for 2 hours. The mixture was then allowed to cool to 0 ° C and then filtered. The solid was washed with water (15 mL) and acetone (15 mL) and dried in vacuo to give 4.34 g (96%) of 9- (2-hydroxyethoxymethyl) guanine, m.p. 255-257 ° C.

li

Claims (9)

9 i '- Claims. A process for the preparation of compounds of formula (I): .:: R λγ \, ^ X) CH 2 OCH-> CH 2 OH where k is amino or hydroxy, still known in the presence of a lysed base of formula Yi.cist according to (II) <- R] oi v (H) X "~ C-Nlv \ N / 0 Cf ^ 0 CII2C1 1jO - (! - X2 where» · * - is hydroxy or -NR ^ .CX and X 2 and X 2 are the same and are each an alkyl or phenyl group and k '') · -CXL, provided that when K "1 'is hydroxy, it is hydrogen. «? 1 I. i vitun 1.1 The process according to claim 1, ί n n \ ·· i i t ä, took an alkyl group containing J-U carbon Lomia. A method according to claim 1 or 2, 12. . i u n n e t t u that X and X are similar and k. sr .. ·> · o n m c t y y 1 i r y h mä. A method according to any one of the preceding claims, characterized in that e is an aqueous 1 o n; V ohol imito primary 'ui secondary1 is ali f.ru + t i .: * «-> o: /. a jl k oxy in alcohol or water pi another t.ji alkoholini 'öö oy. r 'f \: 10 641 60 Process according to any one of the preceding claims, characterized in that the compound of formula (II) is prepared by reacting guanine or 2-aminoadenine in which the 2- and 9- or 2-, 6- and 9-positions are acylated with 2 -oxa-1,4-butanediol diester in the presence of a catalytic amount of a strong acid. Process according to Claim 5, characterized in that the acid catalyst is p-toluenesulfonic acid. An intermediate of formula (II) R1 useful in the process according to claim 1. » R.Λ> X'-C-NIt ^ \ N / I ^ l'ii2 oc: u2ciijo- c-x2 1 2 112 where R is hydroxy or -NR .CX, and X and X are the same It 0 2 or different and each is an alkyl or phenyl group, and R is 11-12 hydrogen or -CX, provided that when R is hydroxy, R is hydrogen. Joy Intermediate according to Claim 7, characterized in that the alkyl group contains 1 to 4 carbon atoms. Intermediate according to Claim 7 or 8, characterized in that X and X are the same and each is a methyl group. n 64160 Patentkrav.