Reaction of Tetracyanoethylene with Arylazoaminopyrazoles via charge‐transfer complexation

Abstract
Arylazoaminopyrazoles (1a–d) reacts with tetracyanoethylene (TCNE) to yield pyrazolo[1,5‐a]pyrimidines (9) via charge‐transfer (CT) complex formation. The effect of the substituents on the basicity of the pyrazole nucleus as well as the complexation centre in different types of pyrazoles is discussed.