Chiralimidodiphosphoric acid-catalysed asymmetric functionalization of 3-hydroxy bisindoles was established. Sulfur-containing groups could be successfully introduced into isatin frameworks using commercially available thiols. The transformation was compatible with substrates bearing distinct substituents, both aromatic and aliphatic thiols were amenable to afford the desired products. A total of
The oxindole-embedded ortho-quinone methides were employed as reactive intermediates in formal [4 + 2] annulation with 1,3-dicarbonyls, providing an efficient access to spiro[chromen-4,3'-oxindole] scaffolds via a cascade conjugate addition/ketalization/dehydration process. This protocol featured metal-free conditions, wide substrate scope, and excellent yields.