The catalytic asymmetric dearomatization of tryptamine for accessing <i>meso</i>-contiguous quaternary carbon centers of oligomeric cyclotryptamine alkaloids: a formal synthesis of hodgkinsine B

Abstract

Herein, we disclosed a catalytic asymmetric dearomatization (CADA) of tryptamine <italic>via</italic> tandem [4 + 2] cycloaddition/cyclization with <italic>o</italic>-azaxylylene <italic>in situ</italic> generated from functionalized 3-bromooxindole promoted by chiral <italic>N</italic>,<italic>N</italic>′-dioxide/Ni(BF₄)₂.