Photochemistry and Photooxidation of Acylsilanes

The photochemistry and photooxidation of three acylsilanes formyltrimethylsilane ( 1a ), acetyltrimethylsilane ( 1b ), and benzoyltrimethylsilane ( 1c ) has been studied in argon and O 2 -doped argon matrices. UV irradiation in argon very slowly results in the decarbonylation of 1a and 1b, while 1c is stable under these conditions. The major photoproduct of 1b is trimethyl(vinyloxy)silane. In O 2 -doped argon matrices irradiation leads to the insertion of an O 2 molecule into the Si−CO bond. Other oxidation products observed are the trimethylsilyl esters of the corresponding carboxylic acids and carbonates. These results can be rationalized if we assume that the primary photoprocesses of 1 are α-cleavage of the Si−CO bond to give radical pairs and [1,2]-silyl shifts to give siloxycarbenes.