Synthesis of pyrazolo[1,5-a]pyrimidines in the reaction of 5-amino-3-arylpyrazoles with methoxymethylene Meldrum's acid derivatives and thermolysis of their pyrazolylaminomethylene derivatives

Abstract

A series of pyrazolo[1,5-a]pyrimidin-3-ones 3 was prepared from Meldrum's acid and 5-amino-3-arylpyrazoles 1 by cyclization in nitrobenzene of the corresponding 5-pyrazolylaminomethylene Meldrum's acid derivatives 2. The structure of pyrazolo[1,5-a]pyrimidin-3-ones and their precursors were determined by nmr measurements.