A Convenient Deoxygenation of Sulfoxides with CO(II) and NaBH₄

Abstract

Complex species, presumably transition metal hydrides, prepared from NaBH₄ and transition metal salts have been used in the reduction of nitro, cyano, halo and amido functional groups.¹ We recently reported that Co (II) and NaBH₄ in ethanol reduced alkenes and alkynes in high yields, and that the regent displayed remarkable steric selectivity in the reduction of alkenes: mono>di>tri- and tetra-substituted alkenes.² We now report that the same reagent could be conveniently employed for the efficient reduction of sulfoxides to sulfides. A number of conditions have previously been reported to deoxygenate sulfoxides to sulfides in varying yields: for example, SO⁹ ₃, etc.