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

Highly effective and stereoselective enamine-singletoxygen couplingwas achieved by synergistic chiral primary amine and photocatalysisin hexafluoroisopropanol. The current enamine catalysis enables alpha-hydroxylation of beta-ketocarbonylswith good yields and high enantioselectivity across a broad rangeof substrates. Mechanistic studies revealed a direct participationof solvents in the critical enamine coupling step, and a solvent-O-1(2) H-bonding mode was invoked to account for thedramatic solvent effect.

Automated summary

Highly effective and stereoselective enamine-singletoxygen coupling was achieved by synergistic chiral primary amine and photocatalysis in hexafluoroisopropanol. The current enamine catalysis enables alpha-hydroxylation of beta-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-O-1(2) H-bonding mode was invoked to account for the dramatic solvent effect.