Asymmetric Synthesis of Trisubstituted Tetrahydrothiophenes via in Situ Generated Chiral Fluoride-Catalyzed Cascade Sulfa-Michael/Aldol Reaction of 1,4-Dithiane-2,5-diol and α,β-Unsaturated Ketones

A chiral, fluoride-catalyzed asymmetric cascade sulfaMichael/aldol condensation reaction of 1,4-dithiane-2,5-diol and a series of alpha,beta-unsaturated ketones is described to access chiral trisubstituted tetrahydrothiophene derivatives. The target products, including the spiro tetrahydrothiophene derivatives bearing a five-, six-, and seven-membered ring, were highly functionalized and showed high ee value. This established protocol realized a highly enantioselective reaction with a catalytic amount of KF and Song's chiral oligoEG via in situ generated chiral fluoride to construct useful heterocyclic skeletons with great complexity.