Novel Catalytic Enantioselective Protonation (Proton Transfer) in Michael Addition of Benzenethiol to α-Acrylacrylates: Synthesis of (S)-Naproxen and α-Arylpropionic Acids or Esters.

A novel synthesis of optically active 2-phenylpropionic acids or esters via catalytic enantioselective protonation in the Michael addition of benzenethiol to 2-phenylacrylates is described; the synthetic utility is further demonstrated by the asymmetric synthesis of (S)-Naproxen.