We have developed a method for constructing tricyclic [1,2-a]indoles via nickel-catalyzed intramolecular imine-alkene coupling reactions. This method enables syntheses of 6-5-5 and 6-5-6 tricyclic [1,2-a]indoles. The use of NIXantphos or DPPPent as a ligand and 4-(trifluoromethyl)benzoic acid as a co-catalyst is crucial for the reaction. The synthetic utility of the method was demonstrated by converting the product into useful indole amines.

中文翻译：

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镍催化分子内亚胺-烯烃偶联合成三环[1,2-a]吲哚

我们开发了一种通过镍催化的分子内亚胺-烯烃偶联反应构建三环 [1,2- a ] 吲哚的方法。该方法能够合成 6-5-5 和 6-5-6 三环 [1,2- a ] 吲哚。使用 NIXantphos 或 DPPPent 作为配体和 4-(三氟甲基)苯甲酸作为助催化剂对反应至关重要。该方法的合成效用通过将产物转化为有用的吲哚胺来证明。