Entry to Heterocycles Based on Indium‐Catalyzed Conia‐Ene Reactions: Asymmetric Synthesis of (−)‐Salinosporamide A

Abstract

Conica can: The In(OTf)3-catalyzed cyclization of nitrogen- and oxygen-tethered acetylenic malonic esters gives five- to seven-membered heterocycles in moderate to excellent yields (see scheme; Tf=trifluoromethanesulfonyl). The asymmetric synthesis of (−)-salinosporamide A illustrates the synthetic utility of the method.