Photochemical Michael Addition of Indoles to α,β‐Unsaturated Ketones utilizing Arylazo Sulfones as the Photoacid Generators

Abstract The Michael‐type addition of indoles represents one of the most important C−C bonds forming reactions at their C‐3 position. Herein, we present a mild, versatile and sustainable protocol for the efficient preparation of β ‐indolylketones via a Michael addition between indoles and chalcones or α , β ‐unsaturated ketones in the presence of substituted arylazo sulfones as photoacid generators (PAGs).