Synthesis of hydrazone derivatives by reaction of azines with nitriles, and their transformation into pyrazoles and pyrimidones

Abstract

Reaction of equimolar amounts of saturated nitriles and azines affords hydrazone derivatives; with unsymmetrical azines the reaction is regioselective and takes place with an alkyl substituent at the end of the azines opposite to an aryl substituent. Acid catalysed cyclisation and hydrolysis of the hydrazone derivatives yields N-unsubstituted pyrazoles, whereas aluminium chloride catalysed cyclisation of the N-ethoxycarbonyl analogues affords pyrimidones.