Microwave Assisted Domino Knoevenagel Condensation/6pi-electron Electrocyclization Reactions for the Rapid and Efficient Synthesis of Substituted 2H,5H-pyrano[4,3-6]pyran-5-ones and Related Heterocycles

摘要

Both natural and unnatural compounds with a 2H,5H-pyrano[4,3-b]pyran-5-one skeleton are of interest to medicinal chemistry as they exhibit several different biological activities. This heterocyclic ring systems is accessible by a Domino Knoevenagel condensation/6jr-electron electrocyclization. A simple and rapid microwave assisted protocol of this Domino process has been developed for the preparation of libraries of substituted 2H,5H-pyia-no[4,3-b]pyran-5-ones and related heterocyclic systems in a single preparative step by reaction of an alpha,beta-unsaturated aldehyde with a 6-substituted 4-hydroxy-2H-pyran-2-one.