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.