Organocatalytic Asymmetric α‑Sulfenylation of 2‑Substituted Indolin-3-ones: A Strategy for the Synthesis of Chiral 2,2-Disubstituted Indole-3-ones with S- and N‑Containing Heteroquaternary Carbon Stereocenter

An organocatalytic asymmetric α-sulfenylation of 2-substituted indolin-3-ones with N-(alkylthio or arylthio)­succinimides has been developed for the first time using Cinchona-derived squaramide as the catalyst. Various chiral 2,2-disubstituted indole-3-ones with S- and N-containing heteroquaternary carbon stereocenters were obtained with up to 98% yield and 99% ee.