Bleasdale C, Cameron R, Edwards C, Golding B T
Department of Chemistry, University of Newcastle upon Tyne, U.K.
Chem Res Toxicol. 1997 Dec;10(12):1314-8. doi: 10.1021/tx970122d.
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.
用二甲基二氧杂环丙烷（DMDO）氧化7-氧杂双环[4.1.0]庚-2,4-二烯（苯氧化物）/氧杂环庚三烯，主要生成（Z,Z）-粘康醛，具有完全的非对映选择性。类似地，2-甲基-7-氧杂双环[4.1.0]庚-2,4-二烯（甲苯1,2-环氧化物）/2-甲基氧杂环庚三烯生成（Z,Z）-1,6-二氧代庚-2,4-二烯，而2,6-二甲基-7-氧杂双环[4.1.0]庚-2,4-二烯（1,2-二甲基苯1,2-环氧化物）/2,7-二甲基氧杂环庚三烯生成（Z,Z）-2,7-二氧代-3,5-辛二烯。通过1H NMR光谱监测苯氧化物/氧杂环庚三烯的DMDO氧化反应，确定一种重要的副产物为4,8-二氧杂双环[5.1.0]辛-2,5-二烯（对称氧杂环庚三烯氧化物）。这一观察结果支持了以下假设：生成（Z,Z）-粘康醛的途径是从氧杂环庚三烯经6,8-二氧杂双环[5.1.0]辛-2,4-二烯（氧杂环庚三烯2,3-氧化物）进行的，有一条次要途径生成对称氧杂环庚三烯氧化物。所描述的DMDO氧化反应为苯的细胞色素P450依赖性代谢以及苯系烃的大气光氧化提供了模型体系。
