91057-65-7Relevant academic research and scientific papers
Thermal and bromide ion-catalyzed rearrangement of benzofuran dioxetanes to 1-oxaspiro[2.5]octa-5,7-dien-4-ones
Adam, Waldemar,Ahrweiler, Michael,Reinhard, Dirk
, p. 6713 - 6718 (2007/10/02)
The reaction of the tetrasubstituted benzofuran dioxetanes 2 with various nucleophiles, e.g. Br-, Cl-, I-, and HN(i-Pr)2, was investigated and the unprecedented bromide ion-catalyzed rearrangement to the hithert
Ring Cleavage of Benzofurans and Tetrahydrobenzofurans by m-Chloroperbenzoic Acid Epoxidation
Adam, Waldemar,Ahrweiler, Michael,Sauter, Markus
, p. 941 - 946 (2007/10/02)
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. - Key Words: 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
Chemical Model Studies on the Mutagenesis of Benzofuran Dioxetanes in the Ames Test: Evidence for the Benzofuran Epoxide as Ultimate Mutagen
Adam,Hadjiarapoglou,Mosandl,Saha-M?ller,Wild
, p. 8005 - 8011 (2007/10/02)
The synthesis of the first benzofuran epoxide 3a was achieved by epoxidation of the benzofuran 1a with dimethyldioxirane and alternatively by deoxygenation of the benzofuran dioxetane 2a with sulfides. This labile epoxide formed with nucleophiles such as water, methanol, thiophenol, and imidazole the corresponding adducts 13a-16a. In contrast to epoxide 3a, the dioxetanes 2 required acid catalysis (CF3CO2H) for the addition of water, methanol, and azide ion to give the corresponding adducts 9-11; in the absence of nucleophiles the allylic hydroperoxides 8 were formed. The decomposition of benzofuran dioxetanes 2 in the polar, protic solvents water and methanol afforded not only the expected cleavage products 4 but also the 1,3-dioxols 5, the spiroepoxide dimer 6a, and the 1,4-dioxines 7. An intramolecular electron-transfer mechanism is postulated for the formation of the spiroepoxide, which subsequently dimerizes to 6a or rearranges into 5 and 7. Only the benzofuran epoxide 3a, besides the benzofuran dioxetanes 2, was mutagenic in the Salmonella typhimurium strain TA100. Therefore, we implicate the epoxide 3a as the ultimate mutagen responsible for the high mutagenic activity observed with dioxetane 2a in the Ames test. We postulate that in the oxidative metabolism of polycyclic arenes and heteroarenes the corresponding epoxides are generated from the intermediary dioxetanes by deoxygenation with sulfides.
