Sc(OTf)3‐Catalyzed Ring‐Opening Reactions of Donor‐Acceptor Cyclopropanes/Bicyclo[1.1.0]butanes: Access to 3‐Substituted Chromenones, Cyclopenta[b]chromenones and 2‐Aminobicyclo[2.1.1]hexanes

Abstract A robust Sc(OTf) 3 ‐catalyzed and DBN‐assisted strain‐release‐driven ring‐opening‐annulation reaction of ortho ‐hydroxyarylenaminones with an array of 2‐aryl‐substituted cyclopropane 1,1‐diesters as perfect 3 C atoms reactive synthons to create three new C−C, C−O, and C−C bonds sequentially is reported. This one‐pot two‐step process concocts various value‐added poly‐substituted tetrahydrocyclopenta[ b ]chromenones in reasonable yields with excellent diastereoselectivities. Pleasantly, this newly developed Lewis acid‐catalyzed technique also facilitates the strain‐release driven ring‐opening reactions involving highly strained bicyclo[1.1.0]butanes as enamine acceptors, endowing the quick access to synthetically challenging 2‐aminobicyclo[2.1.1]hexanes and α‐cyclobutyl‐ β ‐arylacrylaldehydes with excellent diastereoselectivities.