Asymmetric aza-Friedel–Crafts reaction of newly developed ketimines: access to chiral indeno[1,2-<i>b</i>]quinoxaline architectures

The functionalized 11-amino-indeno[1,2-<i>b</i>]quinoxaline scaffold is a pivotal structural motif in diverse bioactive compounds. In this study, we developed a chiral phosphoric acid catalysed enantioselective aza-Friedel-Crafts reaction between indeno[1,2-<i>b</i>]quinoxalin-11-imines and indoles. This methodology enables the synthesis of chiral hybrid architectures incorporating both 11-aminoindeno[1,2-<i>b</i>]quinoxaline and indole moieties, achieving exceptional synthetic efficiency (up to 99% yield) with outstanding stereocontrol (up to 99% ee).