Direct oxidative dearomatization of indoles: access to structurally diverse 2,2-disubstituted indolin-3-ones

Chem Commun (Camb). 2019 Jun 11;55(46):6535-6538. doi: 10.1039/c9cc02956g. Epub 2019 May 20.

Abstract

Described is an efficient oxidative dearomatization of indoles with TEMPO oxoammonium salt and a broad range of nucleophiles. Under very mild conditions, dearomative oxyalkynylation and oxyalkenylation of indoles to structurally diverse 2,2-disubstituted indolin-3-ones were developed for the first time with high atom-economy. In addition, dearomative oxyarylation, oxyallylation, and oxycyanation of indoles were also demonstrated. Mechanism studies indicated that TEMPO oxoammonium salt served as the sole oxidant source through an electron donor-acceptor (EDA) intermediate.