Stereospecific Reactions of Donor–Acceptor Cyclopropanes with Thioketones: Access to Highly Substituted Tetrahydrothiophenes

Lewis‐acid‐catalyzed reactions of 2‐substituted cyclopropane 1,1‐dicarboxylates with thioketones are described. Highly substituted tetrahydrothiophenes with two adjacent quaternary carbon atoms were obtained in a stereospecific manner under mild conditions and in high yield when using AlCl 3 as Lewis acid. Moreover, an intramolecular approach was successfully implemented to gain access to sulfur‐bridged [ n .2.1] bicyclic ring systems. Conversion of selenoketones, the heavier analogues, under similar conditions resulted in the formation of various tetrahydroselenophenes.