Rh2(OAc)4 and Chiral Phosphoric Acid Cocatalyzed Highly Diastereo- and Enantioselective Four-Component Reactions: Facile Synthesis of Chiral α,β-Diamino Acid Derivatives

A highly diastereo- and enantioselective four-component reaction of a diazo ketone with two molecules of anilines and ethyl glyoxylate was achieved under Rh2(OAc)4 and chiral phosphoric acid cocatalyzed conditions. This transformation proceeds through a Mannich-type trapping of the ammonium ylide generated from metal carbene and one molecule of aniline with iminoester derived from another molecule of aniline and ethyl glyoxylate. With this method, a series of chiral α,β-diamino acid derivatives were efficiently constructed in good yields and with good to excellent diastereo- and enantioselectivities.