A Straightforward Route to Potent Phenolic Chain‐Breaking Antioxidants by Acid‐Promoted Transposition of 1,4‐Benzo[b]oxathiines to Dihydrobenzo[b]thiophenes |
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| Authors: | Dr Caterina Viglianisi Dr Riccardo Amorati Dr Leonardo Di Pietro Prof Stefano Menichetti |
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| Affiliation: | 1. Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3‐13, 50019, Sesto Fiorentino, Firenze (Italy);2. Department of Chemistry “G. Ciamician”, University of Bologna, Via S. Giacomo 11, 40126 Bologna (Italy) |
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| Abstract: | The transformation of simple phenols with limited antioxidant activity into potent chain‐breaking antioxidants was achieved by a three‐step protocol, consisting of the conversion of phenols into 1,4‐benzob]oxathiines followed by an unprecedented acid‐promoted transposition to o‐hydroxydihydrobenzob]thiophenes, or dihydrobenzode]thiochromenes, starting from phenols or naphthols, respectively. These derivatives, bearing a benzo‐fused heterocycle with a sulfide sulfur ortho to the phenolic OH, have a rate constant of reaction with alkylperoxyl radicals (kinh) comparable to that of α‐tocopherol. A solid rationale for the transposition mechanism as well as for the structure‐antioxidant activity relationship is presented. |
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| Keywords: | antioxidants electrophilic substitution phenols S heterocycles vitamins |
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