Siloxycarbenes, formed by the photolysis of dimethyl- or diphenylsilacyclohexanone have been trapped as oxiranes or as the ring-opened hydrolysis products of oxiranes, with simple aldehydes and ketones such as acetaldehyde, or cyclohexanone. The reactions are interpreted as arising from the nucleophilic attack of the siloxycarbene on the carbonyl group. The structures of the oxiranes and their hydrolysis products have been established.
The photolysis of acylsilanes in a variety of polar reagents (alcohols, acetic acid, HCN, pyrrole, etc.) is shown to involve formation of isomeric siloxycarbenes which act as nucleophiles and insert into the polar H—X bonds present in the reagents. With alcohols as solvents, mixed acetals of an aldehyde with 1 mol each of silanol and alcohol are formed, but these subsequently undergo dark, acid-catalyzed reactions, by one of two mechanisms which involve either carbon–oxygen or silicon–oxygen bond cleavage. The acid catalyst appears to be a by-product of the photolysis reaction. Kinetic and stereochemical evidence is presented in support of the proposed reaction pathways.
The photolyses of several acylsilanes and one acylgermane in carbon tetrachloride have been shown to involve Norrish Type I cleavage of the metalloid-acyl bond to give metalloidal radicals. These radicals readily abstract chlorine from the solvent.