Diastereo- and Enantioselective Addition of Anilide-Functionalized Allenoates to N-Acylimines Catalyzed by a Pyridylalanine-Based Peptide

A selective peptide-catalyzed addition of allenic esters to N-acylimines is reported. Tetrasubstituted allenes were achieved with up to 42:1 diastereomeric ratio and 94:6 enantiomeric ratio (up to 99:1 er after recrystallization of the major diastereomer). An exploration of the role of individual amino acids within the peptide was undertaken. The scope of the reaction was explored and revealed heightened reactivity with thioester-containing allenes. A mechanistic framework that may account for the observed reactivity is also described.