Synthesis of Annelated Azaheterocycles Containing a 5‐Carbamoylpyrazin‐3‐one Fragment by a Modification of the Four‐Component Ugi Reaction.

Abstract

A convenient synthesis of novel imidazole- and pyrrole-fused 1-oxo-1,2,3,4-tetrahydropyrazine heterocyclic structures by a novel modification of the four-component Ugi condensation is described. The usefulness and versatility of the developed approach for the synthesis of variously substituted compounds is demonstrated and the scope and limitations of the chemistry involved are discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)