Carbazoquinocin Analogues as Small Molecule Biomimetic Organocatalysts in Dehydrogenative Coupling of Amines.

A new series of carbazole-cored biomimetic ortho -quinone catalysts structurally resembling carbazoquinocin alkaloids have been introduced to promote tunable, metal cocatalyst-free, organocatalytic, dehydrogenative amine oxidation under aerobic conditions. Differently substituted benzyl amines were tolerated under optimized conditions to provide imines in excellent yields. Further efficacy of the catalyst was demonstrated by synthesizing cross-coupled imines efficiently. Control experiments and in-depth DFT studies disclosed a covalent transamination pathway as a plausible mechanism for this newly developed catalytic system.