GB937725A — Pyrazolo[3:4-d]pyrimidines

USPTO Abstract

The invention comprises a pyrazolo [3:4-d] pyrimidine of the formula: <FORM:0937725/IV(a)/1> or a tautomer thereof, in which R1 represents a hydrogen atom or an alkyl, cycloalkyl, cycloalkylalkyl, or aralkyl group or a mononuclear or binuclear aryl group, R3 represents a hydrogen atom or a lower alkyl group, R1 represents a free or aliphatically monosubstituted or aliphatically disubstituted amino group or a hydrazino group and R6 represents an aryl or aralkyl group, physiologically tolerable salts thereof, pharmaceutical preparations thereof and a process for the manufacture thereof wherein a 1-R1-3-R3-6-R6-4-X-pyrazolo-[3:4-d] pyrimidine, in which X represents a reactive esterified hydroxyl group or a free or subtituted mercapto group is treated with hydrazine, ammonia or an amine of the formula R4H in which R4 represents an aliphatically monosubstituted or aliphatically disubstituted amino group. Preferred compounds are compounds of the above formula wherein R1 represents a hydrogen atom or a lower alkyl group, R3 represents a hydrogen atom or a lower alkyl group, R4 represents a di-lower-alkylamino, pyrrolidino, piperidino, morpholino or piperazino group and R6 represents a phenyl or benzyl group of which the phenyl group is unsubstituted or mono-, di- or trisubstituted by chlorine, methoxy, methylenedioxy, methyl or trifluoromethyl. 1-Isopropyl- 4-hydroxy- 6-phenyl-pyrazolo [3,4-d] pyrimidine is obtained by heating 2-isopropyl-3-aminopyrazole 4-carboxylic acid amide with benzoic acid amide and treating the product with sodium hydroxide. 1-Isopropyl- 4-chloro- 6-phenylpyrazolo [3:4-d] pyrimidine is obtained by refluxing the corresponding 4-hydroxy compound with phosphorous oxychloride. 1-R1-3-R3-4-SH-pyrazolo- [3:4-d]-pyrimidine is obtained by treating the corresponding 4-hydroxy compound with a sulphurising agent, e.g. P2S5. Said pharmaceutical preparations having coronary-dilating properties and containing the above compounds are employed enterally or parenterally in tablets or dragees, or in liquid form as solutions, suspensions or emulsions. Specifications 937,722, 937,724 and 937,726 are referred to.