Stereospecific Reaction of Donor-Acceptor Cyclopropanes with Thioketones : A Novel 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 using AlCl3 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 analogs, under similar conditions resulted in the formation of various tetrahydroselenophenes.