The first chiral phosphoric acid-catalyzed formal 6+1 cycloaddition of (2-aminobenzyl)indoles with isatins has been developed, efficiently affording biologically important chiral indoloazepine-based spirooxindoles in high yields (up to 99%) and excellent enantioselectivities (up to 97:3 er). Notably, this novel class of chiral indoloazepine-based spirooxindoles exhibits potent cytotoxicity against human liver cancer cell line HepG2.
Wu et al. (Sun,) studied this question.