Azo Coupling of Indoles Revisited: Synthesis of Biindolyl Photoswitches via the Azo-Coupling/C-H Functionalization Domino Approach.

When azo coupling of aryldiazonium salts with indoles was carried out in aprotic nonpolar solvent on air, a pseudo-three-component reaction has been discovered. Azo coupling is followed by a nucleophilic addition of a second indole unit to the indolium intermediate; aromatization and oxidation are achieved under air.

Electrochemical Decarbonylative Aminosulfonylation of Alkynes with Sulfinates and N-(Formyl)anilides.

An unprecedented electrochemical three-component reaction of phenylacetylene, sulfinate, and N-(formyl)anilide was discovered. The transformation occurs in an undivided cell with a graphite anode and cathode in DMF in the presence of tetrabutylammonium iodide as an electrolyte. The addition of silver(I) oxide and catalytic amounts of iodine facilitated the reaction significantly. The transformation was also carried out under photoredox-catalyzed conditions.