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Photochemical Reactions. 153th communication. Photochemistry of acylsilanes: Photolyses and thermolyses of α,β-epoxy silyl ketones

✍ Scribed by Markus E. Scheller; Bruno Frei

Publisher
John Wiley and Sons
Year
1992
Tongue
German
Weight
567 KB
Volume
75
Category
Article
ISSN
0018-019X

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✦ Synopsis

The photolyses and thermolyses of the cc,l(-epoxy silyl ketones 5 and 6 are described. On n,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(cx-0 bond and subsequent C(l)+C(2) migration of the (t-Bu)Me,Si 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 viu a siloxycarbene intermediate. In addition, the 1,3-dioxole 10 was formed via an initial C(cc )-C(l() 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. ') 152nd communication, see [I].

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