Ruthenium-triggered ring opening of ethynylcyclopropanes: [3+2] cycloaddition with aldehydes and aldimines involving metal allenylidene intermediates

Abstract

It's complex: Ruthenium-catalyzed [3+2] cycloaddition of ethynylcyclopropanes with aldehydes and aldimines has been found to give the corresponding 2-ethynyltetrahydrofurans or -pyrrolidines in high to excellent yields. In both cases, the formation of a ruthenium allenylidene complex as a key reactive intermediate is supported by density functional theory calculations. Cp=η5-C5Me5. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.