Pyrimidine Derivatives and Related Compounds, I Synthesis of Some 2, 3-Disubstituted-4, 5, 6, 7-Tetrahydropyrazolo[l, 5-a]-Pyrimidine Derivatives

Abstract

The 5-aminopyrazole derivatives (la-c) react with acrylonitrile to yield the corresponding l-β-cyanoethyl-5-aminopyrazole derivatives (2a-c) which could be readily cyclised into the corresponding pyrazolo[l, 5-a]pyrimidines (3a-c). Under similar conditions la-c has failed to react with methylacrylonitrile or methyl methactylate. However, when the reaction of la-d with these reagents was conducted in ethanolic sodium ethoxide, the pyrazolo[l, 5-a]pyrimidine derivatives (3d-f) were formed. Structures of resulting products was established by their synthesis via interaction of β-cyanoethylhydrazine (4) and β-cyanopropylhydrazine (10) with the appropriate β-bifunctionalnitrile. Compounds la, b also reacted with methyl phenylpropiolate to yield the pyrazolo[l, 5-a]pyrimidine derivatives (18). © 1975, Walter de Gruyter. All rights reserved.