Oxidation of 8-Methoxypsoralen (8-MOP) by Dimethyldioxirane. Evidence for the Formation of a Furocoumarin Epoxide by Methanol Trapping, a Potential Mutagenic Agent
✍ Scribed by Adam, Waldemar ;Sauter, Markus
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 233 KB
- Volume
- 1992
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
The reaction of 8‐methoxypsoralen (1) with dimethyldioxirane in methanol at 25^°^C yields the methanol adduct 3, namely the 2,3‐dihydro‐2‐hydroxy‐3,9‐dimethoxy‐7__H__‐furo[3,2‐g][1]benzopyran‐7‐one, whose structure was unequivocally assigned by means of spectroscopic data. Methanol adduct 3 is produced by dioxirane epoxidation of the furan double bond of 1 to 2 followed by nucleophilic attack by methanol at the benzylically activated C‐3. The direct observation of the 8‐methoxypsoralen epoxide (2) was not possible, because at low temperature (below 0^°^C) dimethyldioxirane does not epoxidize 1, while at 25^°^C this labile epoxide decomposes. On the basis of these results, a rational explanation is offered as to the origin of the regioisomeric methanol adduct 5, namely 2,3‐dihydro‐3‐hydroxy‐2,9‐dimethoxy‐7__H__‐furo[3,2‐g][1]benzopyran‐7‐one, observed in traces (ca. 0.2%), when 1 is treated with sodium hypochlorite and hydrogen peroxide in aqueous methanol.