Reactions of group IV organometallic compounds. Part XIII. Extensive study of the cyclization and insertion reactions of trimethylsilylphosphines with isocyanate
Diphenyltrimethylsilylphosphine was found to be an effective catalyst for cyclization of phenyl isocyanate, affording cyclic dimer and trimer at moderate temperature. An abnormal decarboxylation took place to give diphenylcarbodi-imide and its cyclic trimer above 50°. Evidence for the equilibrium reaction, 3 diphenylcarbodi-imide ⇌ cyclic trimer, was obtained. Phenylbis(trimethylsilyl)phosphine forms a stable 1 : 1 adduct with phenyl isocyanate; its structure is discussed.