Arsonium salts, reductive cleavage

Horner has extended this reaction to the electrochemical reduction of optically active arsonium salts (68, X = As), which also undergo cleavage with retention of stereochemical configuration at arsenic M 65). This is a convenient synthetic route of optically active arsines of known configuration. 

The reductive cleavage of achiral and optically active quaternary phosphonium and arsonium salts with alkali metal amalgams to form tertiary phosphines and arsines succeeds in high yield with retention of configuration [124]. The reduction with the amalgams was found to give better yields than the conventional cathodic cleavage. 

Other Compounds. Horner and co-workers [129-131] have described the production of optically active phosphines and arsines in the cathodic cleavage of quaternary phosphonium and arsonium salts. This reaction, like its reverse quaternization reaction, takes place with retention of configuration. Shapoval, Skobets, and Markova [132, 133] have described the production of a. stereoregular isocyanate polymer during reduction at a nickel cathode in dimethyl-formamide. The formation of a stereoregular product evidently demonstrates the orienting effect of the electrode on the molecules of the monomer in the polymerization process. 

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