In continuation of polycyclic aromatic hydrocarbons (PAH) synthesis via an aryne Diels-Alder cycloaddition and bridge extrusion methodology, we now describe a simple phenanthrene (1) synthesis using this strategy. Phenanthrene is an ubiquitous combustion product in the environment found in coal tar, cigarette smoke, motor vehicle exhaust, green coffee beans, sunflower oil, and other sources. Although phenanthrene is not carcinogenic per se, it has served as a prototypical molecule for biological studies of the carcinogenic benz[a]anthracene, dibenz[a,h]anthracene, benzo[a]pyrene, and other PAH. For example, the human metabolism of (deuterated) phenanthrene has been used as a marker to measure the potential lung cancer susceptibility in cigarette smokers. Moreover, more than 250 natural phenanthrenes have been described, mostly oxygenated analogues from higher plants. While myriad syntheses of substituted phenanthrenes are known, relatively few syntheses of phenanthrene itself exist. The closest example to the present work is that of Jung and Koreeda, who employed an aryne-furan cycloaddition method to prepare 1 and several polymethylated phenanthrenes. Our synthesis of phenanthrene is shown in Scheme 1. The easily synthesized 1bromo-2-fluoronaphthalene (2) is allowed to react with 1-(trimethylsilyl)pyrrole (3) in the presence of magnesium to afford the Diels-Alder cycloadduct 4 in 62% yield after workup. The trimethylsilyl group is cleaved during the dilute acid workup. Deamination of 4 with iso-amyl nitrile gives phenanthrene (1) in 86% yield (78% after sublimation). This simple synthesis of 1, devoid of column chromatography, should be applicable to the synthesis of ring-substituted and deuterated phenanthrenes given the wide availability of substituted pyrroles.

中文翻译：

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菲的简单合成

在通过芳炔 Diels-Alder 环加成和桥挤出方法合成多环芳烃 (PAH) 的过程中，我们现在描述了使用该策略的简单菲 (1) 合成。菲是环境中无处不在的燃烧产物，存在于煤焦油、香烟烟雾、机动车尾气、生咖啡豆、葵花籽油和其他来源中。尽管菲本身不致癌，但它已作为致癌苯并[a]蒽、二苯并[a,h]蒽、苯并[a]芘和其他多环芳烃的生物学研究的原型分子。例如，（氘化）菲的人体代谢已被用作衡量吸烟者潜在肺癌易感性的标志物。此外，已经描述了 250 多种天然菲，主要来自高等植物的含氧类似物。虽然取代菲的无数合成是已知的，但菲本身的合成相对较少。与当前工作最接近的例子是 Jung 和 Koreeda，他们采用芳炔-呋喃环加成法制备 1 和几种多甲基化菲。我们合成菲的过程如方案 1 所示。 容易合成的 1bromo-2-fluoronaphthalene (2) 在镁存在下与 1-(trimethylsilyl)pyrrole (3) 反应得到 Diels-Alder 环加合物 4 in 62处理后的％产率。三甲基甲硅烷基在稀酸后处理过程中被裂解。4 用异戊腈脱氨基得到菲 (1)，产率为 86%（升华后为 78%）。这种简单的合成 1，没有柱层析，