α,β,γ,δ-Unsaturated carbonyl compounds were converted regioselectively into γ-hydroxy-α,β-unsaturated carbonyl compounds by reduction-oxygenation with molecular oxygen and triethylsilane in the presence of cobalt(II) porphyrin as a catalyst followed by treatment with trimethyl phosphite. (±)-6-Hydroxyshogaol and related furanoids isolated from ginger were synthesized via this method.