A re-engineering approach: synthesis of pyrazolo[1,2-a]pyrazoles and pyrano[2,3-c]pyrazoles via an isocyanide-based four-component reaction under solvent-free conditions

摘要

A new protocol based on a re-engineering approach has been developed for the efficient synthesis of pyrazolo[1,2-a]pyrazoles and pyrano[2,3-c]pyrazoles via an isocyanide-based four-component reaction of dialkyl acetylenedicarboxylates, isocyanides, and ethyl acetoacetate with hydrazine hydrate or phenyl hydrazine. The reactions were carried out under solvent- and catalyst-free conditions at mild temperatures and short times in good yields. (C) 2016 Elsevier Ltd. All rights reserved.