the silyl ketone 1 as well as the methyl ketone 2 undergo a Norrish type II reaction involving γ-H-abstraction and fragmentation to the diene 12, and acetone (20) or the acylsilane 26, respectively. The methyl ketone 2, but not the acylsilane 1, isomerizes to cyclobutanols (21A-D). Additionally, compound 1 shows photochemical behavior typical of acylsilanes undergoing rearrangement to the siloxycarbene