Transition Metal-Diene Complexes in Organic Synthesis, Part 22.The Iron-Mediated Quinone Imine Cyclization: A General Route to 3-Hydroxycarbazoles
作者:Hans-Joachim Knölker、Michael Bauermeister、Jörn-Bernd Pannek、Marcus Wolpert
DOI:10.1055/s-1995-4430
日期:1995.4
Electrophilic aromatic substitution of 4-methoxyarylamines 2by the tricarbonyliron-complexed cyclohexadienylium cations 1leading to the iron complexes 3 is described. Chemoselectiveoxidation of the arylamine moiety of the complexes 3 to the quinoneimine and iron-mediated quinone imine cyclization using appropriate oxidizingreagents (activated manganese dioxide or thallium(III) trifluoroacetate) ledto the tricarbonyliron-complexed 4b,8a-dihydrocarbazol-3-ones 5.Demetalation of 5 with trimethylamine N-oxideat room temperature occurred with concomitant aromatization of the organicligand and provided a broad access to the 3-hydroxy-9H-carbazoles 7.
介绍了用三羰基铁络合环己二烯阳离子 1 对 4-甲氧基芳胺 2 进行亲电芳香取代,生成铁络合物 3 的过程。使用适当的氧化试剂(活化的二氧化锰或三氟乙酸铊(III))将络合物 3 的芳胺基团化学选择性氧化为醌亚胺并进行铁介导的醌亚胺环化反应,可得到三羰基铁络合物 4b,8a-二氢咔唑-3-酮 5。室温下,5 与三甲胺 N-氧化物发生脱金属反应,同时有机配体发生芳香化反应,从而获得 3-羟基-9H-咔唑 7。