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 α-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 α-position
and an aliphatic substituent at the β-position were efficiently
obtained with high diastereo- and enantioselectivities.