Enantioselective Formal Alkenylations of Imines Catalyzed by Axially Chiral Dicarboxylic Acid Using Vinylogous Aza-Enamines

摘要

Catalytic asymmetric synthesis of chiral allylic amines has been an extensively studied research field owing to their remarkable synthetic versatility. In this context, catalytic asymmetric alkenylation of imines, though considered to be quite a straightforward process, has only recently become an attractive option toward this end, following the prevalence of asymmetric allylic animation. The rapidly growing field of organocatalysis has played a pivotal role in this latest development as can be seen in the asymmetric Petasis reaction, which gives chiral allylic amines with an electron-rich alkene group being transferred from the corresponding alkenyl boron species.The organocatalytic aza-Morita-Baylis-Hillman reaction, wherein α,β-unsaturated carbonyl compounds formally act as an alkenyl anion at their a position via a catalytically generated ionic intermediate, constitutes another important strategy to afford chiral allylic amines with an electron-withdrawing alkene moiety.