Selective Reduction of Aryl Halides and α,β-Unsaturated Esters with Sodium Borohydride-Cuprous Chloride in Methanol and Its Application to Deuterium Labeling

Article abstract of DOI:10.1021/jo00283a025

A reducing system, NaBH4-Cu2Cl2/MeOH, was developed for dehalogenation of aryl halides, conjugate reduction of α,β-unsaturated esters, and deuterium labeling in a chemo- and regioselective manner.These reactions proceeded without reduction of isolated olefins.The Cu2Cl2 is assumed to function as the catalyst which generates a transient species of copper hydride as an active reducing agent, on contact with NaBH4.Deuterium-labeling studies indicated that (i) the hydrogen which is transferred to the 4-position of methyl 4-iodobenzoate originates from MeOH and (ii) thehydrogens which were transferred to the α- and β-positions of the conjugated ester originate from MeOH and NaBH4, respectively.