The triphenylmethyl radical was discovered by Gomberg in 1900 and has been shown to be a persistent radical species. Surprisingly, this radical is rarely used in organic synthesis since its discovery over a century ago. Here, we report a metal-free aerobic dehydrogenation of N-heterocycles mediated by a triphenylmethyl radical generated from a triaryl carbonium ion pair as the precatalyst in the presence of TEMPO. This protocol exhibits a broad substrate scope and excellent functional group tolerance. The practicality has also been demonstrated with the gram-scale preparation of key intermediates of small-molecule drugs and late-stage functionalization of various dipine drugs. Mechanistic studies and DFT calculations revealed that the triphenylmethyl radical was involved in the catalytic cycle and was essential for the aerobic dehydrogenation process.

Here, we report a highly efficient catalytic species generated from Ph3C+[B(C6F5)4]- in water mediated Friedel-Crafts type reaction of indoles with carbonyl compounds to afford 3,3’-bisindolylmethanes (BIMs). This scalable method is...

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