Herein, we report an aerobic oxidative C−N bond-forming process that enables the facile synthesis of imidazo[1,2a]pyridines and takes advantage of a coupled organocatalytic system that uses flavin and iodine. Furthermore, the dual catalytic system can be applied to the one-pot, three-step synthesis of 3-thioimidazo[1,2-a]pyridines from aminopyridines, ketones, and thiols.

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.

Herein, we demonstrated the oxidative cross-dehydrogenative coupling between amidines and chalcones catalyzed by flavin and iodine. The riboflavin-iodine catalytic system played multiple roles in substrate- and O2-activation, enabling the facile and atom-economical synthesis of tetra-substituted imidazoles in good yields (60–87%). This metal-free reaction consumed only 1 equiv of molecular oxygen and generated 2 equiv of environmentally benign H2O as the only byproduct.

ChemInform Abstract Aminolysis of the title reagent (I) with amino acids is carried out in aqueous medium at pH > 10.