Iridium-Catalyzed Amidation of In Situ Prepared Silyl Ketene Acetals to Access alpha-Amino Esters

Abstract

Disclosed herein is a convenient Ir-catalyzed amidation of esters to access a-amido esters. Initially prepared silyl ketene acetals are directly employed, without separate purification, for subsequent amidation with an oxycarbonylnitrenoid precursor using the Cp*(LX)-Ir(III) catalyst. The alpha-amidation was facile for both alpha-aryl and alpha-alkyl esters. Density functional theory studies revealed that the generation of a putative Ir-nitrenoid is facilitated by the chelation of the countercation additive during the N-O bond cleavage of the nitrene precursor.