Asymmetric α-selective allylation of the amide unit of maleimides and alkenyloxindoles by dual-functional InIII/N,N′-dioxide complex

Abstract

Chiral γ-hydroxy-γ-lactams are versatile building blocks for the synthesis of many important bioactive compounds. Herein, we disclose a regio- and enantioselective direct α-selective allylation of the amide moiety of maleimides with potassium allyltrifluoroborates via a dual-functional In^III/N,N′-dioxide complex. This protocol provides a straightforward route to optically active γ-hydroxy-γ-lactams. Additionally, alkenyloxindoles were tolerated as well, affording enantioenriched 2-allylindolin-2-ols in high yields. The gram-scale synthesis and further transformations of the products demonstrate the potential utility of this method. Based on the experimental studies and DFT calculations, a possible catalytic cycle and transition states are provided to elucidate the regio- and enantioselectivity.