A wide range of derivatives with new pyrido[2,1-a]pyrrolo[3,4-c]isoquinoline skeleton was synthesized by free-radical intramolecular cyclization of o-bromophenyl-substituted pyrrolylpyridinium salts using the (TMS)₃SiH/AIBN system. The cyclization provides generally good yields of pyrido[2,1-a]pyrrolo[3,4-c]isoquinoline hydrobromides having no additional radical-sensitive substituents. The free bases can be obtained from the synthesized hydrobromides in quantitative yield by basification at room temperature. The selectivity control of intramolecular arylation was achieved by replacing the halogen: the use of 1-(2-(ortho-bromophenyl)-4-(ortho-iodophenyl)pyrrol-3-yl)pyridinium bromide makes it possible to obtain a monocyclization product, and the bicyclization product from the dibromo derivative. The procedure is also applicable to obtain 3-arylpyrido[2,1-a]pyrrolo[3,2-c]isoquinoline derivatives including 2-unsubstituted skeletons that are inaccessible via Pd-catalyzed cyclization.

中文翻译：

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含吡咯和吡啶环的多杂环的自由基环化方法

使用 (TMS) ₃ SiH/AIBN通过邻溴苯基取代的吡咯基吡啶鎓盐的自由基分子内环化合成了一系列具有新的吡啶并[2,1- a ]吡咯并[3,4- c ]异喹啉骨架的衍生物系统。环化通常提供没有额外自由基敏感取代基的吡啶并[2,1- a ]吡咯并[3,4- c ]异喹啉氢溴化物的良好产率。游离碱可以通过在室温下碱化以定量收率从合成的氢溴酸盐中获得。分子内芳基化的选择性控制是通过取代卤素来实现的：使用 1-(2-( ortho- bromophenyl)-4-( ortho-碘苯基)吡咯-3-基)溴化吡啶鎓使得有可能获得单环化产物，并且由二溴衍生物获得双环化产物。该程序也适用于获得 3-芳基吡啶并[ 2,1- a ]吡咯并[3,2- c ]异喹啉衍生物，包括无法通过 Pd 催化环化的 2-未取代骨架。