A general method is described for indirectly effecting radical carbocyclization of an alkyl chain onto an aromatic ring. Birch reductive-alkylation of aromatic tert-butyl esters with α,Ï-dibromides, chromium(VI)-mediated oxidation of the resulting 1,4-dienes and Finkelstein displacement of Brâ with NaI gives cross-conjugated ketones that undergo radical cyclization. The products are easily aromatized to phenols by silylation, Saegusa oxidation and treatment with BiCl3.H2O. A special feature of the route is that it allows attachment of a substituent to the original aromatic ring in place of the phenolic oxygen of the normal product.
一种通用方法被描述用于间接地实现烷基链与芳环的自由基碳环化。通过使用α,ω-二
溴化物对芳香叔丁基酯进行Birch还原烷基化,接着对所得的1,4-二烯进行
铬(VI)介导的氧化,以及用NaI替代Br⁻的Finkelstein反应,可以得到交联共轭酮,这些酮随后经历自由基环化。这些产物可以通过
硅化、Saegusa氧化以及与
BiCl3·
H2O处理,轻松芳香化为
酚类化合物。这条路线的一个特殊之处在于,它允许将取代基附加到原始芳环上,以替代正常产物中的
酚醇氧。