Inspired by the photochemical mechanism of a plant blue-light receptor, a unique flavin-based photocatalytic system was developed for the chemoselective heterocoupling of two different thiols, which enabled the facile synthesis of unsymmetrical disulfides. Owing to the redox- and photo-organocatalysis of flavin, the coupling reaction took place under mild metal-free conditions and visible light irradiation with the use of air, which is recognized as the ideal green oxidant.

The aerobic oxidative cross-coupling of indoles with azoles driven by flavin-iodine-coupled organocatalysis has been developed for the green synthesis of 2-(azol-1-yl)indoles. The coupled organocatalytic system enabled the one-pot threecomponent synthesis of 2-azolyl-3-thioindoles from indoles, azoles, and thiols in an atom-economical manner by utilizing molecular oxygen as the only sacrificial reagent.

The chemoselective electrochemical oxygenation of sulfides to sulfoxides is performed using a biomimetic flavin catalyst that enables the activation of molecular oxygen under a low cathode potential. Diverse functional groups, including alcohols, ketones, aldehydes, cyclopropane, carboxylic acids, pyridine, alkenes, and alkynes, are well tolerated under low‐voltage electrolytic conditions.

A coupled catalysis was performed using a riboflavin-derived organocatalyst and molecular iodine, which successfully promoted the aerobic oxidation of thiols to disulfides under metal-free mild conditions. The activation of molecular oxygen occurred smoothly at room temperature through the transfer of electrons from the iodine catalysis to the biomimetic flavin catalysis, which formed the basis of the green oxidative synthesis of disulfides from thiols.