Abstract Photolysis of 1-alkenyldisilanes, with one exception, afforded silaethene type of silicon—carbon intemediates via photorearrangement of a silyl group to the carbon atom of a vinyl substituent. These intermediates reacted with methanol and methanol-d 1 to give the corresponding methoxysilanes in high yields. With E-2-phenylethenylpentamethyldisilane, UV-irradiation in the presence of methanol gave 1-methoxydimethylsilyl-1-trimethylsilyl-2- ...