Studies on positive inotropic agents. V. Synthesis of 1-heteroaroylpiperazine derivatives.

A series of 1-heteroaroylpiperazines (V-VII, XI) was synthesized and examined for positive inotropic activities on the canine heart. The key intermediates, heteroarenecarboxylic acids (III, X), were prepared by two different methods, and were condensed with substituted piperazines to give 1-heteroaroylpiperazines V-VII and XI. Among them, quinazoline derivatives (XI) were found to have potent positive inotropic activities.