Reactions of group IV organometallic compounds : XXIX. Insertion reactions of (trimethylsilylmethylene)phosphorane with heterocumulenes. Inhibition of Wittig type reactions

Abstract

A reaction of (trimethylsilylmethylene)dimethylphenylphosphorane, PhMe 2PCHSiMe 3 (I), with phenyl isocyanate affords a 2/1 insertion product, which results from insertion of phenyl isocyanate into both the CSi and CH bonds of I. By way of contrast, a reaction of isothiocyanate and carbon disulfide with I affords 1/1 products by insertion of these heterocumulenes into the CSi bond of I. In these reactions, Wittig-type elimination of dimethylphenylphosphine oxide or sulfide did not occur because of irreversible migrations of the trimethylsilyl group to the anionic centers of the Zwitterionic intermediates.