ISSN:
0009-2940
Keywords:
Epoxidation
;
Dioxirane, dimethyl-
;
Benzofurans, 2-methyl-3-phenyl
;
Benzofuran epoxides
;
Quinone methides
;
(Z/E) Photoisomerization
;
Norcaradiene
;
Benzocycloheptafuran
;
Thermal rearrangement
;
Xanthenes, 9-acetyl-
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The photoisomerization of quinone methides 3 to benzocycloheptafuran 4 and the thermolysis of the latter to xanthenes 5 are reported. The quinone methides 3 are accessible by dimethyldioxirane oxidation and subsequent valence isomerization of the resulting benzofuran epoxides 2. On irradiation (λ 〉 400 nm), the quinone methides 3 rearrange by cyclization to the corresponding norcaradiene, and ring enlargement affords the benzocycloheptafurans 4. Thermolysis of the cycloheptatrienes 4 leads to the xanthenes 5, first by cycloreversion to the norcaradienes, followed by electrocyclization to the chromenes and tautomerization of the latter. The new cycloheptatrienes 4 and xanthenes 5 were fully characterized.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931261220
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