Diphenyl (trimethylsilylmethyl) phosphine (1) was allowed to react with benzophenone in the presence of CsF in N, N-dimethylformamide to give a mixture of methyldiphenylphosphine (2),(2, 2-diphenyl-2-trimethylsiloxyethyl) diphenylphosphine (3) and (2-hydroxy-2, 2- diphenylethyl) diphenylphosphine (4) in good yield. The use of about 10 mol% of CsF gave 3 with fairly good selectivity. The reaction with benzaldehyde gave a similar result, but ...