- Redox-neutral decarboxylative photocyclization of anthranilic acids
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A mild metal-, catalyst-, and oxidant-free photoredox neutral system has been found to efficiently enable intramolecular decarboxylative cyclization of anthranilic acids. This facile protocol provides an alternative method for the synthesis of carbazoles. Mechanistic studies reveal a key photoinduced 6π-electrocyclization process and formic acid was released as the sole byproduct.
- Huang, Huawen,Deng, Kun,Deng, Guo-Jun
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p. 8243 - 8247
(2020/12/29)
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- Copper-Catalyzed Cascade Cyclization of Indolyl Homopropargyl Amides: Stereospecific Construction of Bridged Aza-[n.2.1] Skeletons
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Catalytic cycloisomerization-initiated cascade cyclizations of terminal alkynes have received tremendous interest, and been widely used in the facile synthesis of a diverse array of valuable complex heterocycles. However, these tandem reactions have been mostly limited to noble-metal catalysis, and are initiated by an exo-cyclization pathway. Reported herein is an unprecedented copper-catalyzed endo-cyclization-initiated tandem reaction of indolyl homopropargyl amides, where copper catalyzes both the hydroamination and Friedel–Crafts alkylation process. This method allows the practical and atom-economical synthesis of valuable bridged aza-[n.2.1] skeletons (n=3–6) with wide substrate scope, and excellent diastereoselectivity and enantioselectivity by a chirality-transfer strategy. Moreover, the mechanistic rationale for this novel cascade cyclization is also strongly supported by control experiments, and is distinctively different from the related gold catalysis.
- Tan, Tong-De,Zhu, Xin-Qi,Bu, Hao-Zhen,Deng, Guocheng,Chen, Yang-Bo,Liu, Rai-Shung,Ye, Long-Wu
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p. 9632 - 9639
(2019/06/27)
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- Photoinduced Cross-Coupling of Amines with 1,2-Diiodobenzene and Its Application in the Synthesis of Carbazoles
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A facile and efficient process for the preparation of various tertiary aminobenzenes and carbazole derivatives via photoinduced cross-coupling of amines with 1,2-diiodobenzene is reported. Mechanistic investigations indicate that the transformation proceeds via nucleo-philic addition of an amine to the benzyne intermediate accompanied with a proton transfer process, followed by an oxidative cyclization of the generated diphenylamine to furnish the corresponding carbazole products.
- Zhao, Xinxin,Chen, Ming,Huang, Binbin,Yang, Chao,Gao, Yuan,Xia, Wujiong
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p. 2981 - 2989
(2018/05/15)
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- Synthesis of carbazoles by gold(I)-catalyzed carbocyclization of 2-(enynyl)indoles
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A new synthetic protocol for carbazoles through gold(I)-catalyzed intramolecular hydroarylation of (Z)-2-(enynyl)indoles was achieved in good yields. The requisite (Z)-2-(enynyl)indoles were synthesized stereoselectively by trimethylgallium-promoted, Z-selective Wittig olefination of N-alkylindole-2-carboxaldehydes with propargyl ylides. Substrates possessing both alkyl as well as aromatic groups are well tolerated under these reaction conditions. Georg Thieme Verlag Stuttgart.
- Praveen, Chandrasekaran,Perumal, Paramasivan Thirumalai
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p. 521 - 524
(2011/04/17)
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- Platinum-Catalyzed Intramolecular Alkylation of Indoles with Unactivated Olefins
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Reaction of 1-methy-2-(4-pentenyl)indole (1) with a catalytic amount of PtCl2 (2 mol %) in dioxane that contained a trace of HCl (5 mol %) at 60 °C for 24 h led to the isolation of 4,9-dimethyl-2,3,4,9-tetrahydro-1H-carbazole (2) in 92% yield. Platinum-catalyzed cyclization of 2-(4-pentenyl)indoles tolerated substitution at each position of the 4-pentenyl chain. Furthermore, the protocol was applicable to the synthesis of tetrahydro-β-carbolinones and was effective for cyclization of unprotected indoles. 2-(3-Butenyl)indoles underwent platinum-catalyzed cyclization with exclusive 6-endo-trig regioselectivity. Mechanistic studies established a mechanism for the platinum-catalyzed cyclization of 2-alkenyl indoles involving nucleophilic attack of the indole on a platinum-complexed olefin. Copyright
- Liu, Cong,Han, Xiaoqing,Wang, Xiang,Widenhoefer, Ross A.
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p. 3700 - 3701
(2007/10/03)
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