ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The preparation and photolyses of the diepoxyenones (E)-8 and (E)-9 as well as the diepoxydiene (E)-10 are described. On 1π,π*-excitation (λ = 254 nm), the diastereoisomeric diepoxyenones (E)-8 and (E)-9 undergo isomerization via the ylide intermediate f and the carbene intermediate g leading to the primary photoproducts 17A and 18-21 (Scheme 8). On 1n, π*-excitation (λ 〉 347 nm), (E)-8 shows behaviour typical of epoxyenones undergoing C(γ), O-bond cleavage of the oxirane and isomerization to compounds 22, (E/Z)-23 and (E)-24 (Scheme 10). On singlet excitation, the diepoxydiene (E)-10, is cleaved to the carbonyl ylide j and the carbenes 1 and m (Scheme 11). The carbonyl ylide j fragments via the dipolar intermediate k to the acetylenic dienone (E)-31. The carbene 1, showing behaviour typical of vinyl carbenes, furnishes the cyclopropene 30. The alternative carbene m, however, undergoes an insertion reaction into the neighboring oxirane C,C-bond leading to the proposed but not isolated oxetene 43, which is further transformed to the products 33A _ B by an intramolecular cycloaddition.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19840670323
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