Abstract The reaction of diazomethane with hexamethyl-, 1, 1, 2, 2, 3-pentamethyl-2-ethyl- and 1, 1, 2, 2, 3-pentamethylsilirane in diethyl ether solution resulted in (formal) CH 2 insertion into the SiC 2 ring to give silacyclobutanes as products. The reaction of methylenetrimethylphosphorane with hexamethylsilirane produced a new phosphorus ylide, Me 2 CHCMe 2 SiMe 2 CHP+ Me 3.
