Trapping of an Ammonium Ylide with Activated Ketones: Synthesis of β-Hydroxy-α-Amino Esters with Adjacent Quaternary Stereocenters

A novel Rh-2(OAc)(4)-catalyzed three-component reaction of diazoacetates, anilines, and activated ketones via ammonium ylide trapping processes is reported. The reaction of isatins afforded alpha-amino-beta-hydroxy esters bearing the 3-substituted 3-hydroxyindolin-2-one moiety with vicinal quaternary carbon centers in one step with high chemo- and diastereoselectivity. Extension of the reaction to acyclic a-keto esters afforded 2-hydroxy-2-alkyl-3-aryl-3-(phenylamino) succinates in moderate yield and diastercoselectivity.