ISSN:
0009-2940
Keywords:
Epoxidation
;
Benzofuran
;
Benzofuran epoxide
;
Quinone methide
;
Benzofuran-2-one
;
2,4-Cyclohexadien-1-one, spiroepoxide
;
cis-Ene dione
;
Perester, β-hydroxy-
;
1,3-Benzodioxole
;
Keto enol ester
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The oxidation of the benzofurans 1a-f (tetrahydrobenzofurans 1g, h) with excess m-CPBA is reported. The in situ generated, highly reactive benzofuran epoxides 2a-f and their quinone methides 3a-f (cis-ene diones 3g, h) afford the labile tautomeric peroxy esters 5 and 5′ by nucleophilic addition of the peroxy acid. On elimination of m-chlorobenzoic acid, the peroxy esters 5/5′ of the benzofuran derivatives 1a-f rearrange thermally to the keto esters 6 by C—C cleavage or to the spiro epoxides 7 by C—O cleavage. The latter undergo thermal isomerization to the 1,3-benzodioxoles 8 and Diels-Alder cycloaddition to the corresponding dimers 9. Independently, the keto esters 6 and the 1,3-dioxoles 8 were synthesized by thermolysis of the dioxetanes 11. The tautomeric m-CPBA adducts 5/5′ of the persistent ene diones 3g, h, derived from the tetrahydrobenzofuran derivatives 1g, h, rearrange as well to the spiro epoxides 7g, h. In contrast to the benzofuran derivatives 6a-f, the keto enol ester 6h suffers Baeyer-Villiger rearrangement with another molecule of m-CPBA to form the ene diester 10h.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941270523
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