Reaction of 4-cyano-5-aminopyrazole and 3,4-dicyano-5-aminopyrazole with dimethylformamide diethylacetal

Abstract

The condensation of 4-cyano-5-aminopyrazole or 3,4-dicyano-5-aminopyrazole with dimethylformamide diethylacetal was studied. It was shown that, in addition to the formation of dimethylaminomethyleneamino derivatives, alkylation of the pyrazole ring occurs under severe conditions without a solvent. Only the corresponding formamidino derivatives are formed when the same reactions are carried out in methanal under milder conditions. The site of addition of an ethyl group to the pyrazole ring in the N-alkyl derivatives obtained was established by 13C NMR and PMR spectroscopy. The possibility of the synthesis of 4-amino- or 4-methylmercaptopyrazolo[3,4-d]pyrimidines by cyclization of the corresponding dimethylamino- methyleneaminopyrazoles with a cyano group in the ortho position was demonstrated for the first time.