A versatile, inexpensive and sustainable protocol for the preparation of valuable bis-indolyl methanes visible light-mediated, metal-free Friedel-Crafts arylation has been developed. The procedure, that exploits the peculiar behavior of arylazo sulfones as non-ionic photoacid generators (PAGs), was applied to the conversion of a variety of aliphatic and aromatic aldehydes into diarylmethanes in good to highly satisfactory yields, employing a low-catalyst loading (0.5 mol%) and irradiation at 456 nm.

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http://dx.doi.org/10.1039/d2ob02214aDOI Listing

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