Photochemical Reactions Photochemistry of Acylsilanes: Photolyses and Thermolyses of α,β-Epoxy Silyl Ketones

Article abstract of DOI:10.1002/hlca.19920750105

The photolyses and thermolyses of the α,β-epoxy silyl ketones 5 and 6 are described.On n,?^*-excitation, the silyl ketones 5 and 6 were transformed to the ketone 7 and the ketene 8 in quantitative yield.The formation of 8 may be explained by initial cleavage of the C(α)-O bond and subsequent C(1) -> C(2) migration of the (t-Bu)Me2Si group.In contrast to the acylsilanes 5 and 6, the photolyses of the analogous methyl ketones 11 and 12 gave a very complex mixture of products.On thermolysis, 5 and 6 yielded the ketone 7 and the acetylenic compound 9, which were probably formed via a siloxycarbene intermediate.In addition, the 1,3- dioxole 10 was formed via an initial C(α)-C(β) bond cleavage leading to the ylide g and subsequent intramolecular addition of the carbonyl group.The analogous 1,3-dioxole 13 was obtained on pyrolysis of the methyl ketones 11 and 12.