Visible Light-Promoted Enantioselective Aerobic Hydroxylation of β-Ketocarbonyls by Chiral Primary Amine Catalysis

Highly effective and stereoselective enamine-singlet oxygen coupling was achieved by synergistic chiral primary amine and photocatalysis in hexafluoroisopropanol. The current enamine catalysis enables α-hydroxylation of β-ketocarbonyls with good yields and high enantioselectivity across a broad range of substrates. Mechanistic studies revealed a direct participation of solvents in the critical enamine coupling step, and a solvent-1O2 H-bonding mode was invoked to account for the dramatic solvent effect.