The formation of pyrazolo[1,5‐<i>a</i>]pyrimidines by the reaction of 3‐(4‐chlorophenyl)pyrazol‐5‐amine with chalcones

Abstract

Abstract Cyclocondensation reactions of the pyrazol‐5‐amine 1 and the 1‐aryl‐3‐phenyl‐2‐propen‐1‐ones 2a‐d yield the 6,7‐dihydropyrazolo[1,5‐ a ]pyrimidines 7a‐d . Whereas 7a‐c can be isolated in pure state, 7d is subjected to a spontaneous oxidation.