Chiral Phosphoric Acid Catalyzed Diastereo- and Enantioselective Mannich-Type Reaction between Enamides and Thiazolones

An enantioselective Mannich-type reaction between enamides, serving as aliphatic imine equivalents, and thiazolones or an azlactone, serving as alpha-amino acid derived pronucleophiles, was investigated using a chiral-phosphoric acid catalyst. By using thiazolones, Mannich adducts with a tetrasubstituted chiral carbon center at the alpha-position and an aliphatic substituent at the beta-position were efficiently obtained with high diastereo- and enantioselectivities.