Pyrolysis of methylsilyl phenyl ketones. Formation of silene in the decomposition of an intermediate silaoxetane

Abstract

Methylsilyl phenyl ketones isomerized thermally to siloxyphenylcarbenes which underwent intramolecular insertion into the CH bond of a silyl-methyl group to give an unstable silaoxetane intermediate. The thermal decomposition of the silaoxetane proceeded by cleavage of both the silicon-carbon and the silicon-oxygen bonds. The scission of the SiC bond gave styrene and an SiO doublebonded intermediate which trimerized to a cyclotrisiloxane. On the other hand, the scission of the SiO bond yielded benzaldehyde and an unstable silene. The intermediacy of the latter was supported by the occurence of a Wittig-type reaction with the starting silyl phenyl ketone or benzophenone.