USE OF HEXACHLORODISILANE AS A REDUCING AGENT . STEREOSPECIFIC DEOXYGENATION OF ACYCLIC PHOSPHINE OXIDES

Optically active acyclic phosphine oxides are reduced by hexachlorodisilane to phosphines with a high degree of stereospecificity and with inversion of configuration. Mechanisms for these deoxygenations are suggested which account for the observed stereochemistry. Factors are discussed which are responsible for the racemization of the produced phosphines under the conditions of the reduction. The ready availability of hexachlorodisilane, the simplicity and mildness of the reduction conditions, the high product yield, and the high stereospecificity of the reaction make this a most convenient method for the preparation of optically active phosphines from phosphine oxides. In an extension of this study, octachlorotrisilane was found to reduce acyclic phosphine oxides to phosphines with nearly complete inversion of configuration, and hexachlorodisilane was found to reduce amine oxides to amines and sulfoxides to sulfides. It is suggested that perchloropolysilanes may also be implicated in the reduction of optically active phosphine oxides with trichlorosilane in the presence of strongly basic tertiary amines. © 1969, American Chemical Society. All rights reserved.