ChemInform Abstract: Efficient Synthesis of 1‐Aryl‐4‐[(ethoxycarbonyl)oxy]‐1H‐pyrazole‐3‐carboxylates.

Abstract

Azo‐coupling of diazonium salts (II) with chloroacetoacetate, followed by intramolecular cyclization of hydrazones (III) in the presence of ethyl chloroformate (V) under basic conditions yields a novel family of pyrazoles (VI), instead of the expected hydrazone derivatives.