Bismuth(III)-Triflate-Catalyzed Highly Diastereoselective Synthesis of Substituted Tetrahydrothiophene via Tandem Isomerization, Michael and Aldol Reactions

Bismuth(III)trifluoromethanesulfonate (Bi(OTf)(3)) catalyzes the reaction of beta,gamma-unsaturated ketone and 1,4-dithiane-2,5-diol to afford highly substituted tetrahydrothiophenes via sequential rearrangement, Michael and aldol reactions in good yields. The reaction is highly diastereoselective. Bi(OTf)(3) acts as a catalyst for all three reactions.