title: Catalytic asymmetric direct alpha-amination reactions of 2-keto esters: a simple synthetic approach to optically active syn-beta-amino-alpha-hydroxy esters.
abstract: The catalytic enantioselective direct alpha-amination reaction of 2-keto esters with easily available azo dicarboxylates as the nitrogen source and chiral bisoxazoline-copper(II) complexes as the catalyst is presented. The reactions proceed with excellent enantioselectivities and high yields. The scope of the reaction is demonstrated by the direct amination of a series of 2-keto esters having different substituent patterns. The reaction provides an easy catalytic route to optically active syn-beta-amino-alpha-hydroxy esters, as demonstrated for the synthesis of masked syn-beta-amino-alpha-hydroxy esters (as oxazolidinones) and N-Boc-syn-beta-amino-alpha-hydroxy esters. On the basis of the absolute configuration of the products a tentative model for the transition state is suggested.
authors.affiliation: Center for Metal Catalyzed Reactions, Department of Chemistry, Aarhus University, DK-8000 Aarhus C, Denmark.
authors.forename: Karsten
authors.initials: K
authors.lastname: Juhl
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen