Conjugate reduction and reductive aldol cyclization of α,β-unsaturated thioesters catalyzed by (BDP)CuH.

A conjugate reduction of α,β-unsaturated thioesters catalyzed by copper hydride using PMHS as stoichiometric reductant has been developed. 1,2-Bis(diphenylphosphino)benzene (BDP) was the most effective ligand for this reduction. Saturated thioesters could be produced in excellent yields when the substituent on the thiol is not sterically-demanding. This protocol was applied to induce the reductive aldol cyclization of keto-enethioates, which could offer β-hydroxythioesters in moderate to good yields.