Switchable divergent synthesis of chiral indole derivatives catalytic asymmetric dearomatization of 2,3-disubstituted indoles.

A strategy allowing the switchable divergent synthesis of chiral indole derivatives was established chiral phosphoric acid-catalyzed asymmetric dearomatization of 2,3-disubstituted indoles using naphthoquinone monoimines as electrophiles. The products were switched between chiral indolenines and fused indolines according to the post-processing conditions. Both two types of products were obtained in good to high yields with generally excellent enantioselectivities. NaBH was found to work as a promoter as well as a reductant in the cyclization process leading to fused indolines.