CS199665B2 - Process for preparing 9-substituted purines - Google Patents

Description

The present invention relates to 9-substituted purines and pharmaceutically acceptable salts thereof, and processes for their preparation. In particular, the present invention relates to esters of 9- (2-hydroxyethoxymethyl) guanine a derivatives

2,6-dlaminopurine and pharmaceutically acceptable salts thereof.

It has now been found that the substituted purines of formula I

^from II O (l) where

R ¹ is hydroxyl or amino,

R ² is hydrogen, unbranched or branched alkyl having 2-16 carbon atoms, have antiviral activity against various species of DNA and RNA viruses in vitro and against DNA viruses in vivo. In particular, the compounds are effective against herpes, vaccinia and rhino viruses, wherein the herpes viruses include simplex, zoster and varicella in mammals that cause diseases such as herpes keratitis in rabbits and herpes encephalitis in mice.

According to the present invention, compounds of formula I are prepared wherein R ¹ and R ² are as defined above, or salts thereof, especially in the form of pharmaceutically acceptable salts.

Compounds of formula I wherein R ¹ is hydroxyl or a salt thereof are preferred as well as compounds wherein R ² is a hydrogen atom or a branched or unbranched alkyl group having 2 to 8 carbon atoms, and most preferably compounds having 2 to 4 carbon atoms .

Most preferred compounds are 9- (2-formyloxyethoxymethyl) guanine, 9- (2-propionyloxyethoxymethyl) guanine, 9- (2- (2,2-dimethylpropionyloxyjethoxymethyl) guanine and 2 amino-9- (2-formylloxyethoxymethyl) adenine, especially for their outstanding antiviral activity against Herpes.

Salts which are particularly suitable for therapeutic use are the salts of pharmaceutically acceptable organic acids, such as lactic, acetic, malonic or p-toluenesulfonic acid, as well as salts of pharmaceutically acceptable mineral acids, such as hydrochloric acid or sulfuric acid. When R ¹ is hydroxyl, pharmaceutically acceptable alkali metal salts, preferably sodium salts, may be used. Other salts may also be prepared and then converted into salts directly usable for therapeutic purposes.

The present invention relates to a process for the preparation of a 9-substituted purine of formula I as defined above, characterized in that the compound of formula II

where

R ¹ has the abovementioned meaning and

Q is hydrogen or an alkali metal, reacted with a compound of formula III

A.CH2.O.CH2.CH2.OC.R2 (ni)

II o

where

A is a leaving atom or group and

R ² has the abovementioned meaning, and if the product is a base, converting optionally the product into a salt with an acid or an alkali metal salt or where the product is a salt compound of formula I, converting the salt optionally in the base or another salt thereof.

In this method, the leaving group A is preferably a reactive residue of an organic or inorganic acid and can thus be a halogen atom or a sulfonate group and Q is a hydrogen or alkali metal atom, preferably sodium. A preferred method comprises condensing a purine containing the desired 2- and 6-substitution with an acyl protected 2-halomethaxyethanol or an acyl protected acyloxymethoxyethanol, e.g. The reaction is preferably carried out at room temperature for a longer period of time, for example several hours or even days, required to obtain a sufficient yield.

The method applies to intermediates that can be prepared from simply substituted purines. These purines are, of course, readily available by commonly known literature and textbook procedures such as "Heterocyclic Compounds - Fused Pyrimidines Part II" Purines D.J. Brown (1971) by Wiley-Interscience.

The effect of the compounds of the present invention is demonstrated by the following test:

Inhibition test on plates

The plate inhibition assay was performed on VERO cells in which a flowing monolayer was infected with sufficient virus to produce a uniform coating on the plate. After addition of the solid overcoat layer, a filter paper disc impregnated with a test compound solution (50 µg / disc) is placed in the center of the plate on the solid cover layer. The cultures are incubated for 96 to 120 hours at 37 ° C in an atmosphere of 5% carbon dioxide. After this time, the cells are fixed with 10% formalin and then stained with 0.05 why. methylred. The results are summarized in Table 1.

Table 1

Compound Effect on herpes

9- (2-formyloxyethoxymethyl) guanine - | - (2-amino-9- (2-hydroxyethoxymethyl) adenine +

9- (2-hexanoyloxymethyl) guanine-9- (2-propionyloxyethoxymethyl) guanine - (9- [2- (2,2'-dimethylpropinoyloxy) ethoxymethyl] guanine +

9- (2-palmitoyloxyethoxymethyl) guanine -9- (2-butyryloxyethoxymethyl) guanine + —j- zone greater than 25 mm in diameter -j- zone 5–25 mm + zone 0–5 mm - negative

According to another feature, the present invention relates to a pharmaceutical composition comprising a compound of formula I as defined above or a pharmaceutically acceptable salt thereof together with a pharmaceutically acceptable carrier. According to a feature, the pharmaceutical composition comprises a compound of Formula I in an effective unit dosage form.

As used above, the term "effective unit dose" refers to a predetermined antiviral amount sufficient to act against viruses in vivo. Pharmaceutically acceptable carriers are substances useful for drug applications and may be solid, liquid or gaseous and which are otherwise inert and pharmaceutically suitable and compatible with the active ingredients.

The pharmaceutical compositions can be administered parenterally, orally, used as suppositories or pessaries, topically applied as ointments, creams, aerosols, powders, or applied as eye drops or no199665 su, etc. depending on whether the preparation is to be used. for treating internal or external viral infection.

For internal infections, the composition may be administered orally or parenterally at doses rt / y calculated on the free base of from about 0.1 to 250 mg per kg, preferably 1 to 50 mg / kg of mammalian body weight, and when used in unit dosage forms in in humans, these may be administered several times a day in an amount of from 1 to 250 mg per unit dose.

For oral administration, the fine powders or granules may contain diluents, dispersants and / or surfactants and may be drinkable as a gulp, in water or syrup, may be solids in capsules or wafers or in the form of non-aqueous solutions or suspensions, in which suspending agents may be present, in the form of tablets which may contain binders and lubricants, or in the form of suspensions in water or syrup. If desired or necessary, flavoring, preservative, suspending, thickening or emulsifying agents may also be present. Tablets and granules are most preferred and may be coated.

For parenteral administration or for administration in the form of drops, for example for ocular infections, the compounds may be present in the form of an aqueous solution at a concentration of from about 0.1 to 10%, preferably from 0.1 to 1%, most preferably from 0.1 to 10%. 0.2% w / v The solution may contain antioxidants, buffers and the like.

Alternatively, for infection of the eye or other external tissue such as the mouth and skin, the compositions are preferably applied to the infected part of the patient's body in the form of an ointment, for example in a water-soluble ointment or cream base, for example as an oil in an aqueous cream base. 0.1 to 10%, preferably from 0.3 to 3%, most preferably 1% w / v.

According to another feature, the present invention relates to a method of treating viral infections in mammals, characterized in that an effective unit dose as defined above is administered to a compound of formula I or a pharmaceutically acceptable salt thereof. The application is preferably topical or oral or parenteral.

The present invention is illustrated by the following examples.

Example 1

Preparation of 9- (2-propionyloxyethoxymethyl) guanine.

A. Ethylene glycol (31 g, propionic acid (18.5 g) and 7.5 g of strong cation exchanger in 100 ml of toluene) was stirred and heated to boiling for 18 hours using a Dean Stark trap.

The toluene was removed by evaporation and the remaining liquid was distilled. The initial ethylene glycol precursor is followed by distillation of the desired ethylene glycol monopropionate product. NMR analysis is used to determine purity.

Yield 70%.

B. Anhydrous hydrogen chloride is introduced into a stirred susperise (0 ° C) of ethylene glycol monopropionate (7.1 gj prepared above and paraformaldehyde (1.8 g) in dichloromethane (50 mL)) until all solids have dissolved and the mixture is saturated After drying with molecular sieves and calcium chloride, the mixture is filtered and the solvent is evaporated at 30 ° C.

The remaining oil 2-propionyloxyethoxymethyl chloride was used directly. Yield 60 why.

C. Sodium hydride (2.53 g) A 57% dispersion in mineral oil was washed with anhydrous hexane and added to a solution of guanine (4.53 g in 100 ml of anhydrous dimethylsulfoxide) and the mixture was stirred at 30 ° C for 23 hours.

2-Propionyloxyethoxymethyl chloride (5.5 g) was added and the reaction mixture was stirred at 20 ° C for 18 h. The solution was filtered and the solvent was evaporated in vacuo. The residue was cooled in an ice bath, dissolved in water and neutralized with acetic acid.

After standing for 1 hour, the product was filtered off, washed with water and dried. Crystallization (3X) from boiling acetonitrile gave 9- (2-propionyloxyethoxymethyl) guanine (35%), mp 223-226 ° C.

Example 2

Preparation of 9- (2-dodecanoyloxyethoxymethyl) -2,6-diaminopurine.

I. Anhydrous hydrogen chloride was introduced into a cooled (0 ° C) suspension of ethylene glycol monododecanoate (14.66 g) and paraformaldehyde (1.8 g) in dichloromethane (50 ml) until all solids dissolved and the mixture was saturated with hydrogen chloride.

After drying the solution with molecular sieves and calcium chloride, the mixture was filtered and the solvent was evaporated at 30 ° C.

The residual oil, 2-dodecanoyloxyethoxymethyl chloride was used directly. Yield 75%.

II. An anhydrous solution of 2,6-diaminopurine in dimethylformamide is prepared by heating

3.54 g of monohydrate in 250 ml of solvent, on a steam bath until all solids have dissolved, cooled and allowed to stand for 18 hours over freshly dried molecular sieves.

To this mixture was added 0.95 g of a 57% dispersion of sodium hydride in mineral oil. After stirring the suspension overnight, 2-dodecanoyloxyethoxymethyl chloride (6.35 g) was added dropwise and the reaction mixture was stirred overnight at room temperature.

The solids were filtered, washed with chloroform, and the combined washings and mother liquors were evaporated at 60 ° C.

The residual oil was crystallized from ethanol. Yield 20%.

Example 3

Tablets containing a mixture of 9- (2-formyloxyethoxymethyl) guanine (100 mg), lactose (200 mg), starch (50 mg), lpyrrolidone (5 mg), and magnesium stearate (4 mg) poles are prepared by wet granulation.

Example 4

Tablets containing a mixture of 2-amino-9- (2-formyloxyethoxymethyl iadenine (100 mg), lactose (200 mg), starch (50 mg), wool poles of 1-pyrrolidone (5 mg) and magnesium stearate (4 mg) are prepared by wet granulation.

Example 5

Tablets containing a mixture of 9- (2-propionyloxyethoxymethyl) guanine (100 mg), lactose (200 mg), starch (50 mg) polyvinylpyrrolidone (5 mg) and magnesium stearate (4 mg) are prepared by wet granulation.

Example 6

Tablets containing a mixture of 9- [2- (2,2'-dimethylpropionyloxy) ethoxymethyl] guanine (100 mg), lactose (200 mg), starch (50 mg), polyvinylpyrrolldone (5 mg) and magnesium stearate (4 mg) is prepared by wet granulation.

Claims (4)

A process for the preparation of 9-substituted purines of formula I O (I) where R ¹ is hydroxy or amino, R ² is hydrogen, unbranched or branched alkyl having 2-16 carbon atoms and their salts, wherein the compound of formula II wherein VYNALEZU R ¹ has the abovementioned meaning and Q is hydrogen or an alkali metal, reacted with a compound of formula III A.CH2.O.CH2.CH2.OC.R ² (III) II o where A is a leaving atom or group and R ² has the abovementioned meaning, and if the product of the above reaction is a base, converting the optionally this product to a salt with acid or alkali metal, or if the product salt of a compound of formula I is converted, if desired, the salt on its base or on another salt. 2. A method according to claim 1, characterized in that starting from compounds of the formulas II and III, the leaving atom or group A is a reactive residue of an organic or inorganic acid Q is hydrogen or an alkali metal and R ¹ and R ² have the abovementioned meanings. 3. The method according to claim 2, characterized in that starting from a compound of formula III, wherein the leaving atom or group A is a halogen atom or a sulfonate group and R ² is as defined above. 4. Method according to claim 3, characterized in that starting from compounds of formulas II and III wherein A is halogen, Q is hydrogen, R ¹ and R ² are as defined above and the reaction is carried out in the presence of a base.