The combination of a Pd(0) complex with benzoic acid converts propargylic tryptamines to the corresponding tetrahydro-β-carbolines. The method uses unprotected indoles and affords the desired products with ample functional group tolerance. Detailed modeling studies reveal a close synergy between the organic and metal catalysts, which enables sequential alkyne isomerization, indole C–H activation, and eventual C–C reductive elimination to afford the target heterocycles.

中文翻译：

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钯/羧酸联合催化合成咔啉

Pd（0）配合物与苯甲酸的组合可将炔丙基色胺转化为相应的四氢-β-咔啉。该方法使用未保护的吲哚，并提供具有足够官能团耐受性的所需产物。详细的建模研究表明，有机催化剂和金属催化剂之间具有密切的协同作用，从而可以实现顺序炔烃异构化，吲哚C–H活化以及最终的C–C还原消除以提供目标杂环。