ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The syntheses, photolyses, and thermolyses of the α,β-unsaturated silyl ketones (E/Z)-7, (E)-8, and (E)-9 are described. On n,π*-excitation (λ 〉 347 mm), the aforementioned compounds undergo (E/Z)-isomerization followed by γ-H abstraction. The intermediate enols are trapped intermolecularly by siloxycarbenes leading to the dimeric acetals 27A + B, 30A + B, and 31A + B. In addition, the acylsilanes (E/Z)-7 undergo photoisomerization by δ-H abstraction furnishing the acylsilanes 29A + B. Flash vacuum thermolyses (FVT) of (E/Z)-7, (E/Z)-8, and (E)-9 give rise to intramolecular reactions of the siloxycarbene intermediates. Thus, FVT (520°) of (E)- and (Z)-7 selectively leads to the enol silyl ethers 32 and (E)-33, respectively, arising from carbene insertion into an allylic C--H bond. FVT of (E/Z)-8 (560°) and (E)-9 (600°) affords the trienol silyl ethers 34A + B and the cyclic silyl ethers 37A + B, respectively, which are formed by CH insertion of the siloxycarbenes. As further products of (E)-8 and (E)-9, the bicyclic enol ethers 35 and 36 are formed, presumably via siloxycarbene addition to the cyclohexene C=C bond.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19860690612
Permalink
