Dimethyldioxirane converts benzene oxide/oxepin into (Z,Z)-muconaldehyde and sym-oxepin oxide: modeling the metabolism of benzene and its photooxidative degradation.
Oxidation of 7-oxabicyclo[4.1.0]hepta-2,4-diene (benzene oxide)/oxepin with dimethyldioxirane (DMDO) gave mainly (Z,Z)-muconaldehyde, with complete diastereoselectivity. Similarly, 2-methyl-7-oxabicyclo[4.1.0]hepta-2,4-diene (toluene 1,2-epoxide)/2-methyloxepin gave (Z,Z)-1,6-dioxohepta-2,4-diene, while 2,6-dimethyl-7-oxabicyclo[4.1.0]hepta-2,4-diene (1,2-dimethylbenzene 1,2-epoxide)/2,7-dimethyloxepin gave (Z,Z)-2,7-dioxo-3,5-octadiene. By monitoring the DMDO oxidation of benzene oxide/oxepin by 1H NMR spectroscopy, a significant byproduct was identified as 4,8-dioxabicyclo[5.1.0]octa-2,5-diene (sym-oxepin oxide). This observation supports the hypothesis that the route to (Z,Z)-muconaldehyde proceeds from oxepin via 6,8-dioxabicyclo[5.1.0]octa-2,4-diene (oxepin 2,3-oxide), with a minor pathway leading to sym-oxepin oxide. The DMDO oxidations described provide model systems for the cytochrome P450-dependent metabolism of benzene and for the atmospheric photooxidation of benzenoid hydrocarbons.
Bleasdale
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Department of Chemistry, University of Newcastle upon Tyne, U.K.
Cameron
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Edwards
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Golding
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D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001554:Benzene / Q000378:metabolism*; D003510:Cyclohexanes / Q000737:chemistry / Q000378:metabolism*; D004852:Epoxy Compounds / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D008956:Models, Chemical; D010082:Oxepins / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D010777:Photochemistry
D000447:Aldehydes; D003510:Cyclohexanes; D004852:Epoxy Compounds; D010082:Oxepins; C034476:muconaldehyde; D001554:Benzene; C064455:dimethyldioxirane; C023372:benzene oxide