Photoredox-Catalyzed Cross-Coupling of Enamides for the Assembly of β-Difluoroimine Synthons.

A photoredox-catalyzed formal Csp3-Csp3 cross-coupling reaction of enamides with bromodifluoro compounds is established. The resulting gem-difluoromethylenated γ-imines indicated high stability, excellent E/Z control, and broad functional group tolerance. These synthetic intermediates can efficiently transfer to difluoromethylenated γ-amino acids or δ-amino alcohols. Mechanistic analysis indicates that a radical/SET mechanism proceeding via a difluoroalkyl radical may be involved in the catalytic cycle.