Chiral Nonracemic Pyridine Thiols and Thioethers Applied in Palladium-Catalyzed Allylic Substitution. An Example of Near-Perfect Enantioselection

Pyridine thiols and dithiols have been synthesized by base-induced addition of 2,6-lutidine to thiofenchone. These thiols were converted to their thioether derivatives by alkylation. Application of these compounds in palladium-catalyzed allylic substitution on 1,3-diphenylprop-2-enyl acetate gave nearly absolute enantiomeric excess (98%) and high chemical yield (96%). Isolation of a palladium allylic intermediate gave insight in the origin of chiral recognition for these systems.