Enantioselective Synthesis of N,S‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis

Enantioselective Synthesis of N,S‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis: Reported is the first enantioselective oxidative Pummerer-type transformation using phase-transfer catalysis to deliver enantioenriched sulfur-bearing heterocycles. This reaction includes the direct oxidation of sulfides to a thionium intermediate, followed by an asymmetric intramolecular nucleophilic addition to form chiral cyclic N,S-acetals with moderate to high enantioselectivites.