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Photocycloaddition of Cyclohex-2-enones to Penta-1,2,4-triene

✍ Scribed by Britta Lohmeyer; Kerstin Schmidt; Paul Margaretha

Publisher
John Wiley and Sons
Year
2006
Tongue
German
Weight
86 KB
Volume
89
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

Dihydrothiinone 9a undergoes photocycloaddition regioselectively to all three CC bonds of penta‐1,2,4‐triene (10), the relative stabilities of the biradical intermediates determining the product distribution. In contrast, cyclohexenone 9b and dihydropyranone 9c afford more complex mixtures of bicyclo[4.2.0]octanones, which also turn out to be less stable on chromatographic workup, reflecting the higher strain due to the shorter bond lengths (CO and CC vs. CS) in the six‐membered rings, respectively.

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