Metal-Free Atom-Economical Synthesis of Tetra-Substituted Imidazoles via Flavin-Iodine Catalyzed Aerobic Cross-Dehydrogenative Coupling of Amidines and Chalcones

Abstract

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.

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