CS203095B2 - Process for preparing substituted purines - Google Patents

Description

The present invention relates to substituted purines and pharmaceutically acceptable salts thereof, and to processes for their preparation. More specifically, the invention relates to 9- (2-hydroxyethoxymethyl) purine derivatives such as adenine, guanine, thioguanine and 2,6-diaminopurine, and pharmaceutically acceptable salts thereof. In 1971 Schaeffer et al. [Meed. Chem. 14, 367 (1971)] reported the synthesis of several purine acyclic nucleosides in the study of the interaction of the adenosine deaminase enzyme with the substrate. 9- (2-Hydroxyethoxymethyl) adenine was introduced and its activity measured as an adenosine deaminase substrate.

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

OJ kde

X is an oxygen or sulfur atom; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁵ are different substituents, have antiviral activity against different classes of DNA, RNA viruses, both in vitro and in vivo. In particular, these compounds are effective against cytomegalovirus, adenovirus, in particular adenoivirus 5, rhinovirus, Mengo virus and Sindbis virus. They are particularly effective against vaccine and herpes viruses, including simplex zoster and varicella in mammals that cause diseases such as herpetic keratitis in rabbits and herpetic encephalitis in mice. In addition, they are useful for treating infectious mononucleosis.

The invention relates to compounds of formula I wherein

X is a sulfur or oxygen atom,

R ¹ is hydrogen, alkoxy, azido, halogen, hydroxyl, thio, alkylthio, amino, alkylamino or dialkylamino,

R ² is hydrogen, halogen, amino or azido,

R ³ is hydrogen, straight or branched chain alkyl or cyclic alkyl, hydroxyalkyl, benzyloxyalkyl or phenyl,

R ⁴ is hydrogen, hydroxyl or alkyl,

20309 5

R ⁵ is hydrogen, hydroxyl, amino, alkyl, hydroxyalkyl, benzoyloxy, benzoyloxymethyl, benzoyloxy, sulfamoyloxy, phosphate, carboxypropionyloxy, acetoxy or substituted carbamoyl, of the formula —NH — CO — Z, and Z is alkyl, or Z is alkyl, optionally substituted by one or more groups such as sulfonyl, amino, carbamoyl or halogen,

R ⁶ is hydrogen, alkyl, and when X is oxygen and R ² , R ³ , R ⁴ and R ⁶ are hydrogen, R ¹ is not amino or methylamino when R ⁵ is hydroxyl, hydrogen or benzoyloxy, and also if R ² is hydrogen, R ¹ is not chlorine, or salts thereof, especially pharmaceutically acceptable salts.

Preferred compounds are those compounds of formula I as defined above, wherein

X is an oxygen atom,

R ¹ is hydrogen, halogen, hydroxyl, alkoxy, thio, alkylthio, amino, alkylamino, dialkylamino or azido,

R ² is hydrogen, halogen, amino or azido,

R ³ is hydrogen, straight or branched alkyl or cyclic alkyl, hydroxyalkyl or phenyl,

R ⁴ is hydrogen or hydroxyl,

R ⁵ is hydrogen, hydroxyl, benzoyloxy, hydroxyalkyl, amino, carboxypropionyloxy, acetoxy, benzyloxy, benzoyloxymethyl, phosphate, sulfamoyloxy, substituted carbamoyl of the formula

NH-CO-Z, wherein Z is alkyl, aryl or arylalkyl, optionally substituted with one or more groups such as sulfonyl, amino, carbamoyl, halogen,

R ⁶ is hydrogen, alkyl, wherein R ⁵ is only hydroxyl when R ¹ is amino, hydroxy, alkylamino, alkylthio or dialkylamino and R ² is amino and R ⁶ is hydrogen, R ⁵ is alkylhydroxyl only when R ¹ is hydroxyl, R ⁵ is hydrogen only when R ¹ is hydroxyl or halogen, when R ⁵ is benzoyloxy, R ² is not halogen, R ⁵ is acetoxy only when R ¹ is hydroxyl or amino and R ² is amino or R ¹ and R ² are both halogen atoms, R ⁵ is substituted carbamoyl of the formula NHCO 2, wherein Z is CH (NH 2) CH 2 C 6 H 5 only when R ¹ is a dialkylamino group, except that if R ⁵ is hydroxyl and R ¹ is an alkylamino group, then R ² is not a hydrogen atom, and also when R ² is a hydrogen atom, R ¹ is not a chlorine atom, or a salt thereof, especially a pharmaceutically acceptable salt.

Compounds of formula I as defined above wherein

X is an oxygen atom,

R ¹ is halogen, amino, hydroxy, or alkylthio,

R ² is amino,

R ⁵ is hydroxy, benzoyloxy, carboxypropionyloxy, acetoxy or hydroxyalkyl; and

R ³ , R ⁴ and R ⁶ are hydrogen atoms, where R ⁵ is hydroxyalkyl only when R ¹ is hydroxyl, and R ⁵ is acetoxy only when R ¹ is amino, are most preferred and have been found to be highly active. Compounds where X is sulfur, R ¹ is halogen, amino or alkylamino and R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are hydrogen are also highly active.

A preferred halogen atom is a chlorine atom. Here and throughout the specification, the term alkyl means alkyl having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms.

Salts which are particularly suitable for therapeutic use are salts with pharmaceutically acceptable organic acids, such as lactic, acetic, malonic or p-toluenesulfonic acid, as well as salts with pharmaceutically acceptable mineral acids, such as hydrochloric or sulfuric acid.

According to a second feature, the invention relates to a process for the preparation of substituted purines or their salts of formula I,

where

X, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are as defined above, wherein when X is an oxygen atom and R ² , R ³ , R ⁴ and R ⁶ are hydrogen atoms, R ¹ is not an amino group or methylamino when R ⁵ is hydroxyl, hydrogen or benzyloxy, and also when R ² is hydrogen, R ¹ is not a chlorine atom, or salts thereof, especially pharmaceutically acceptable salts thereof, characterized in that the protecting group is removed from the compound of formula I wherein one or both of R ¹ and R ² are protected and if R ⁵ in the product prepared according to this method is hydroxyl, optionally acylated with a hydroxy group in the compound, and if the reaction product is a base a salt with a sour cell line, or wherein the product is a salt of a compound of Formula I, optionally converting the base salt or other salt.

This method can be R, and R ² are protected for example trimethylsilyl. This compound is the condensation product of trimethylsilylated purine and ester or diesters in a strongly polar solvent such as dimethylformamide or hexamethylphosphoramide and in the presence of a base such as triethylamine or potassium carbonate. The reaction is preferably carried out at room temperature for an extended period of time, for example several days is required for sufficient yield.

These protecting groups are very labile and can be removed by solvolysis with alcoholic or aqueous ammonia or alcoholysis.

Alternatively, the mercuric chloride salt with the purine can be prepared in the presence of alkali and then condensed with a haloether in an aromatic organic type solvent. However, all of the reactive purine substituents must be protected before the salt is prepared, and therefore the last step in this method is the removal of the protecting substituents.

In yet another aspect, the invention relates to pharmaceutical compositions or preparations containing the compound of formula I wherein X is sulfur or oxygen, R ¹ is halogen, hydroxy, thio, alkoxy, azidoskuplna, alkylthio, amino, alkylamino or dialkylamino, R ² is hydrogen , halogen, amino or azido, R ³ is hydrogen, alkyl of straight or branched chain or cyclic alkyl, hydroxyalkyl, benzyloxyalkyl or phenyl, R ⁴ is hydrogen, hydroxy or alkyl, R ⁵ is hydrogen, hydroxy, amino, alkyl, hydroxyalkyl, benzoyloxy, benzoyloxymethyl, benzyloxy, sulfamoyloxy, phosphate, carboxypropionyloxy, acetoxy or substituted carbamoyl of the formula NH-CO-Z, wherein Z is alkyl, aryl or arylalkyl, optionally substituted with one or more sulfonyl, optionally substituted with one or more sulfonyl R ⁶ is an atom in alkyl, wherein the alkyl group R ⁸ has from 1 to 8 carbon atoms and in all other cases the alkyl substituents have from 1 to 4 carbon atoms, 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.

The term "unit dosage form" means a predetermined antiviral amount that is sufficiently effective against viral organisms in vivo.

Pharmaceutically acceptable carriers are materials useful for drug delivery, which may be solid, liquid or gaseous and which are otherwise inert, pharmaceutically acceptable, and compatible with the active ingredients.

These pharmaceutical compositions may be administered parenterally, orally, in the form of suppositories or pessaries, topically applied in the form of ointments, creams or aerosols, powders or as drops in the eyes or nose, and the like, depending on whether the internal or external infection.

For internal infection, the composition is administered orally or patenter at a dose calculated as the free base, from 0.1 to 250 mg per kg body weight, preferably from 1.0 to 50 milligrams per kg mammal weight, and is used in humans in a unit dose. a dosage form to 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, dispersing and / or surfactants and may be applied as infusions in water or syrup, in capsules or cachets in the dry state or as non-aqueous solutions or suspensions which may also contain suspending agents. agents such as tablets, which may contain binders and lubricants, or in the form of a suitable suspension in water or syrup. Where desired and necessary, the preparations may contain flavoring, preservative or suspending, thickening or emulsifying agents. Tablets and granules which may be coated are preferred.

For parenteral administration or for application by drops, for example in ocular infections, the compound may be administered in the form of an aqueous solution in an amount of about 0.1 to 10%, preferably 0.1 to 1%, preferably 0, 2% w / v The solution may still contain antioxidants, buffers and the like.

Alternatively, for infection of the eyes or other external tissues such as the mouth and skin, it is applied topically in the form of an ointment or cream to the infected part of the patient's body. The compounds may be administered in the form of an ointment, for example, in an ointment base which is water-soluble or cream, for example, as an oil in a water-soluble cream base, at a concentration of from 0.1 to 10%, preferably from 0.3 to 3%, preferably 1% w / v;

Among the compounds of formula I, the most preferred are:

9- (2-hydroxy-ethoxymethyl) guanine (R ^{1 =} OH, R ² = s'NH2j and

2-amino-9- (2-hydroxyethoxymethyl) adenine, particularly for its high antiviral activity against herpes viruses. Further compounds

2-amino-6-chloro-9 - [(2-benzoyloxyethoxy) methyl] purine,

9- (2-benzoyloxyethoxymethyl) guanine,

9- (3-hydroxypropoxymethyl) guanine,

Ί

2-amino-6-methylbenzo-9- (2-hydroxyethoxymethyl) purine,

9- [2- (3-Carbonyloxypropionyloxy) ethoxymethyl] guanine,

9- (2-acetoxy-ethoxymethyl) -2,6-diaminopurine,

6-chloro-9-ethylthiomethylpurine,

9-ethylthiomethyladenine,

9-ethylthiomethyl-6-methylaminopurine show high activity against herpes and vaccinia viruses.

In yet another aspect, the invention relates to a method of treating viral infections in a mammal comprising administering to the mammal an effective antiviral amount as defined above, of a substituted purine of formula I or a pharmaceutically acceptable salt thereof. Administration is preferably carried out topically, orally or parenterally.

The invention is illustrated by the following examples.

Example 1

9- (2-hydroxy-ethoxymethyl) guanine (I; R = OH, R ² = NH 2)

A mixture of guanine (2.0 g), ammonium sulfate (1.5 g) and hexamethyldisilazane (126 g) was heated to boiling overnight under a nitrogen atmosphere. The excess hexamethyldisilazane was distilled off under reduced pressure. Dry benzene (10 mL) was added to the remaining oil and the ammonium sulfate was filtered off. To this solution was added triethylamine (4 mL) and a solution of 2-benzoyloxymethyl chloride (2.8 g) in anhydrous benzene (15 mL), and the mixture was heated to reflux overnight under a nitrogen atmosphere. The solvent was removed on a rotary evaporator under reduced pressure and the residue was dissolved in 95% ethanol. The solution was heated on a steam bath for 30 minutes and the silyl groups were hydrolyzed. The ethanol was then evaporated and the residual solid was washed with water, filtered and dried. Crystallization from methanol and then water (the remaining guanine is insoluble in hot solvents and removed by filtration) afforded 9- (2-benzoyloxyethoxymethyl) guanine (0.58 g, 14% of theory) of the theploity, m.p. 222-226 ° C. said condensation of tris- (trimethylsilyl) guanine with a 60% excess of 2-benzoyloxyethoxymethyl chloride gave a 32% yield of 9- (2-benzoyloxyethoxymethyl) guanine.

9- (2-Benizoyloxymethoxymethyl) guanine (0.58 g) and methanol (80 mL) saturated with ammonia were heated in a pressure vessel at 80 ° C for 16 hours. The reaction mixture was removed from the pressure vessel and the solvent was evaporated under reduced pressure. The residue was washed with ether and then crystallized from methanol. There was thus obtained 9- (2-hydroxyethoxymethyl) guanine (0.31 g, 75% of theory), m.p. 256.5-257 ° C.

Example 2

2,6-Diamino-9- (2-benzoyloxyethoxymethyl) purine

A mixture of 2,6-diaminopurine monohydrate (2.0 g), ammonium sulfate (1.32 g) and hexamethyldisilazane (100 g) was heated to reflux under nitrogen for 18 hours. The solvent was evaporated under reduced pressure and the residual oil was dissolved in a minimum amount of benzene. To the benzene solution was added 2-benzoyloxyethoxymethyl chloride (2.56 g), triethylamine (2 mL) and benzene (55 mL), and the reaction mixture was heated to boiling under nitrogen for 18 hours. , 56 g) and triethylamine (2 ml) were heated at reflux for 6 hours, the solvent was evaporated under reduced pressure and the residue was digested in a steam bath in 95% ethanol (40 ml) for 30 minutes. It was recrystallized from ethanol, twice from methanol and finally from water to give 2,6-diamino-9- (2-benzoyloxyethoxymethyl) purine as a yellow solid, m.p. 205 DEG C., yield 7.5%.

Example 3

9- (2- (3-Carboxypropionyloxy) ethoxymethyl] guanine

A mixture of 9- (2-hydroxyethoxymethyl) guanine (0.25 g), succinic anhydride (0.55 g) and pyridine (50 mL) was heated on a steam bath overnight under anhydrous conditions. The solvent was evaporated under reduced pressure at a temperature below 40 ° C, the last traces were removed azetropically with toluene. The residue was triturated in acetone and the product was filtered off. Recrystallization from methanol gave 9- (2- (3-carboxypropionyloxy) ethoxymethyl) guanine, m.p. 20-13-207 ° C (dec. 1.90 ° C) in 44% yield.

Example

9- (3-Hydroxypropoxymethyl) guanine

Sodium benzoate (96.32 g) in dimethylformamide (690 mL) was heated to 80 ° C, and 1-chloro-3-hydroxypropane (63.06 g) was added over 15 minutes. The temperature rose to 135 ° C and the reaction mixture was heated to 135-175 ° C for three hours. 38 g of sodium chloride (97% of theory) were removed by filtration. The filtrate was partially evaporated under reduced pressure below 40 ° C. The concentrated filtrate was poured into ice water and extracted thoroughly with ether. The combined ether extracts were washed with water, dried over anhydrous sodium sulfate and evaporated. The residual oil was distilled on a Vigreux column to give 3-benzoyloxy-1-propanol (85.2 g), bp 124-132 ° C at 0.055 Torr.

Anhydrous hydrogen chloride was bubbled through a solution of 3-benzoyloxy-1-propanol (15.02 g) and paraformaldehyde (2.49 g) in dichloromethane (35 mL) at 0 ° C for one hour. The solvent was evaporated under reduced pressure at a temperature below 40 ° C to give crude 3-benzyloxypropoxymethyl chloride in 92% yield, which was used without further purification.

A solution of trimethylsilyl-guanine in benzene (25 mL), prepared as in Example 1 (from 2.0 g of guanine) containing triethylamine, was heated to boiling and 3-benzoyloxypropoxymethyl chloride (2.96 g) dissolved in benzene (15 g) was added. ml), within three hours. Heat the reaction mixture to reflux under nitrogen overnight. The solvent was removed under reduced pressure and 95% ethanol and methanol were added to the remaining oil. The mixture was heated on a steam bath for several minutes and the solvent was then evaporated under reduced pressure. Chloroform (200 mL) was added and the resulting solid was filtered off. The solid was dissolved in a minimum amount of dimethylformamide, filtered (to remove all guanine) and re-precipitated by the addition of water. Recrystallization from methanol (with activated carbon) gave 9- (3-benzoyloxypropoxymethyl) guanine (0.94 g) as a pale yellow solid, m.p. 198-210 ° C.

A mixture of 9- (3-benzoyloxypropoxymethyl) guanine (0.5 g) and aqueous 45% methylamine (10 mL) was stirred at room temperature overnight. The excess of methylamine and water was evaporated at a temperature below 30 ° C under reduced pressure. the residue was recrystallized from ethanol to give 9- (3-hydroxypropoxymethyl) guanine (0.24 g), m.p. 223 ° C (solidified) as a semihydrate.

Example 5

Oil in aqueous cream base 9- (2-hydroxyethoxymethyl) guanine 5.0 g lanolin, anhydrous 20.0 g polysorbate 60 4.0 g sorbitan monopalmitate 2.0 g light liquid paraffin 4.0 g propylene glycol 5.0 g methylhydroxybenzoate 0 1 g purified water up to 100.0 g

Example 6

Water-soluble ointment base

2-Amino-9- (2-hydroxyethoxy-

methyl) adenine 0.5 glycerine 15.0 macrogol 200 20.0 polyethylene glycol 1500 64.5

Example 7

Tablet - (total weight 359 mg)

9- (2-hydroxyethoxymethyl) -

guanine 100 ALIGN! mg lactose 200 mg starch 50 mg polyvlnylpyrrolidone 5 mg magnesium stearate 4 mg

Example 1 A d

9- (2-Sulfamoyloxyethoxymethyl) adenine

9- (2- (Sulfamoyloxyethoxymethyl) adenine) was prepared as described in Example 3 (m.p. 172-173.5 ° C).

Example B

9- (2- (p-Fluorosulfonylbenzamido) ethoxymethyl] adenine

A mixture of p- (fluorosulfonyl) benzoyl chloride (2.5 g) in tetrahydrofuran (20 ml), 9- (2-aminoethoxyxyimeithyl) adenine (1.58 g) in tetrahydrofuran containing 10% water (100 ml) ) and triethylamine (1.15 g) were stirred at room temperature for one hour. The mixture was poured into 200 ml of water, basified with 5% sodium bicarbonate and extracted three times with chloroform with 10% ethanol. The combined extracts were evaporated to give a white solid which was recrystallized from ethanol to give 9- [2- (p-fluorosulfonylbenzamido) ethoxymethyl] adenine (2.1 g, mp 201-202 ° C).

Example C

9- (2-Bromoacetamidoethoxymethyl) adenine hydrogen oxalate

9- (2-Bromoacetamidoethoxymethyl) -adenine hydrogen oxalate was prepared as described in Example B (m.p. 132-133 ° C).

Example D

9- (2-N-Carbobenzoxyphenylanynylamido-1-ethoxymethyl) adenine

9- (2-Carbobenzoxyphenylalanylamido-1-ethoxymethyl) adenine was prepared as described in Example B (m.p. 208-210 ° C).

Example E

9 - [(2-N-Carbobenzoxyphenylanynyl-amino-1-cyclopentylethoxy) methyl] -6-dimethylaminopurine

9 - [(2-N-Carbobenzoxyphenylalanylamido-1-cyclopentylethoxymethyl) -6-dimethylaminopurine was prepared as described in Example B (m.p. 146-147 ° C).

Example F

9 - [(2-N-Carbobenzoxyphenylalanylamido-1-methylethoxy) methyl] -6-dimethylaminopurine

9 - [(-2-Carbobenzoxyphenylalanylamido-1-methylethoxy) methyl] -6-dimethylaminopurine was prepared as described in Example B (m.p. 149-152 ° C).

Example G

9 - [(2-Phenylalanylamido-1-methylethoxy) methyl] -6-dimethylaminopurine with 1/4 HzO

9 - [(2-Phenylalanylamido-1-methylethoxy) methyl] -6-dimethylaminopurine with 1/4 H 2 O was prepared according to the procedure of Example B (m.p. 77-80 ° C).

Example 1 H d

9 - [(2-Phenylalanylamido-1-phenylethoxy) methyl] -6-dimethylaminopurine with 1/4 L of iso

9 - [(2; Phenylalanylamido-1-phenylethoxy) methyl] -6-dimethylaminopurine with 1/4 H 2 O was prepared by the method described in Example B (melting ~ 135 ° C melts 142-144 ° C),

Claims (2)

Subject A process for the preparation of substituted purines of formula I, ÍD kde R ¹ is hydroxyl, C 1 -C 4 alkoxy, amino, C 1 -C 4 alkylamino or C 1 -C 4 dialkylamino in each alkyl, R ² is hydrogen, halogen, amino or azido, R ³ is hydrogen, straight or branched chain alkyl of 1 to 8 carbon atoms, R ⁵ is hydrogen, hydroxyl, amino, C 1 -C 4 hydroxyalkyl, benzoyloxy, benzoyloxymethyl, benzylVYNALEZ, oxy, sulfamoyloxy, carboxypropionyloxy or acetoxy, or salts thereof, in particular pharmaceutically acceptable salts thereof, characterized in that: Even where R ¹ and / or R ² are protected with a protecting group such as trimethylsilyl, it will remove the protecting group or protecting groups, for example solvolysis or alcoholysis, and if the product of this reaction is a compound where R ⁵ is hydroxyl, it is reacted with an appropriate acylating agent, and if the product of this reaction is a base, optionally converting a compound of formula I to an acid salt, or if the product is a salt of a compound of formula I, optionally converting a salt with a base or another salt. 2. Method according to claim 1 for preparing a compound of formula I wherein R ¹ is amino or hydroxy, R ² is amino, R ³ is hydrogen and R ⁵ is hydroxy, characterized in that the starting compound of Formula I wherein R ¹ and / or R ² are protected with a protecting group such as trimethylsilyl, deprotecting or protecting groups such as solvolysis or alcoholysis.