ISSN:
0009-2940
Keywords:
Oxanorbornadiene → oxepine isomerization, limitations
;
[6 + 4] Tropone dimerization
;
Diene enone [4 + 2] photocycloaddition, intramolecular
;
Oxaquadricyclanes, X-ray structure, thermolysis
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Photochemical Transformations, 761). - Studies in the Area of the Oxanorbornadiene → Oxepine Isomerization. An Intramolecular Diene/Enone [4 + 2] PhotocycloadditionAt room temperature, the “tropone-annulated” oxanorborna diene 2b dimerizes regio- and stereospecifically to give a [6 + 4] adduct (5). Direct photoexcitation of this adduct induces intramolecular diene/enone [4 + 2] addition to 16 followed by a [2 + 2] cycloaddition to provide the dodecacycle 17. An X- ray crystal structure analysis of 17 documents the influence of the heteroatom and of the quasi-bisected ester functions on the length of the three types of oxaquadricyclane - three-membered ring bonds. Direct and sensitized excitation of 2b, c produces polymers; yet, after changing the troponoid chromophor (9, 10) oxaquadricyclane formation takes place (13, 14). In the thermolysis of the annulated oxaquadricyclanes (13, 14) the different cyclopropane C - C bonds are cleaved at a comparable rate.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911241117
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