Chiral Phosphoric Acid‐Catalyzed Asymmetric Oxidation of Aryl Alkyl Sulfides and Aldehyde‐Derived 1,3‐Dithianes: Using Aqueous Hydrogen Peroxide as the Terminal Oxidant

( R )‐1,1′‐Binaphthyl‐2,2′‐diol ( R ‐BINOL) derived chiral phosphoric acids have been explored as organocatalysts for the asymmetric oxidation of a series of aryl alkyl sulfides and 1,3‐dithianes derived from aldehydes with aqueous hydrogen peroxide (H 2 O 2 ) as the terminal oxidant. The enantiomerically enriched sulfoxides are obtained in moderate to excellent yield (up to 99%) with excellent diastereoselectivity (up to >99:1 dr ) and moderate to good enantioselectivity (up to 91:9 er ). In particular, the present protocol stereoselectively provides an efficient access to enantiomerically enriched aryl alkyl sulfoxides and dithioacetal mono‐sulfoxides, which strictly restrains the formation of the undesirable by‐products: sulfones or disulfoxides. The tracking experiments also verify that this approach proceeds via a direct sulfoxidation process, instead of a kinetic resolution route by overoxidation of the resulting sulfoxides.