Selective Formation of Rearranged Silenes from Polysilylenones via 1,3- and 1,5-Silyl Migration

The polysilylenones (E)-1-phenyl-2-pivaloyl-1-(tris(trimethylsilyl)silyl)ethene (E-1a) and (Z)-2-methyl-1-phenyl-2-pivaloyl-1-tris((trimethylsilyl)silyl)ethene (Z-1b) were prepared, and their isomerization under thermal and photochemical conditions was studied. These polysilylenones underwent 1,3- and 1,5-silyl rearrangement selectively, producing the respective silenes, depending on the reaction conditions.