Reaction of lithium (2,4,6-tri-tert-butylphenyl)silylphosphides with haloforms

The reaction of lithium (tert-butyldimethylsilyl)(2,4,6-tri-tert- butylphenyl)phosphide with chloroform afforded (Z)-2-(tert-butyldimethylsilyl)- 2-chloro-1-(2,4,6-tri-tert-butylphenyl)-1- phosphaethene. The NMR study revealed a secondary phosphine resulting from a formal insertion of a dichlorocarbene to the P-Si bond as a reaction intermediate. The reaction is specific to the reactants and substrates. The use of bromoform gave a bromosilylphosphine and a 2- bromo-1-phosphaethene. A less hindered trimethylsilylphosphide afforded bis(2,4,6-tri-tertbutylphenyl) diphosphene.