6933-54-6Relevant academic research and scientific papers
Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
supporting information, p. 13725 - 13729 (2021/09/08)
Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
Tetrahydrocarbazoles by mechanochemical Fischer indolisation
Qiu, Yichen,Puni, Kararaina Te,Duplan, Clotilde C.,Lindsay, Ashley C.,Sperry, Jonathan
supporting information, (2021/05/26)
The Fischer indolisation (FI) typically proceeds in the presence of a Br?nsted or Lewis acid in an organic solvent at elevated temperatures. Herein, we report that tetrahydrocarbazoles (THCs) are accessible by mechanochemical FI at ambient temperature. Using phenylhydrazine hydrochlorides in the presence of silica is critical for this solid-state variant of the FI.
Copper(II) catalyzed aromatization of tetrahydrocarbazole: An unprecedented protocol and its utility towards the synthesis of carbazole alkaloids
Dalvi, Bhakti A.,Lokhande, Pradeep D.
supporting information, p. 2145 - 2149 (2018/05/08)
An efficient protocol for the aromatization of tetrahydrocarbazole is described by using catalytic copper(II) chloride dihydrate in DMSO. This newly established methodology has utilized towards the synthesis of naturally occurring carbazole alkaloids, namely 3-methylcarbazole, 3-formyl carbazole, glycozoline, glycozolicine and clauszoline-K. In addition, the protocol is generalized for the aromatization of N-substituted tetrahydrocarbazole, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline and 1,2,3,4-tetrahydro β-carboline to give the corresponding heteroaromatic compounds from very good to excellent yield. Moreover, this method has been proven to be tolerant to a broad range of functional groups with excellent yields.
A Palladium-Catalyzed Ullmann Cross-Coupling/Reductive Cyclization Route to the Carbazole Natural Products 3-Methyl-9H-carbazole, Glycoborine, Glycozoline, Clauszoline K, Mukonine, and Karapinchamine A
Yan, Qiao,Gin, Emma,Wasinska-Kalwa, Malgorzata,Banwell, Martin G.,Carr, Paul D.
, p. 4148 - 4159 (2017/04/27)
The title natural products 2-7 have been prepared by reductive cyclization of the relevant 2-arylcyclohex-2-en-1-one (e.g. 20) to the corresponding tetrahydrocarbazole and dehydrogenation (aromatization) of this to give the target carbazole (e.g. 4). Compounds such as 20 were prepared using a palladium-catalyzed Ullmann cross-coupling reaction between the appropriate 2-iodocyclohex-2-en-1-one and o-halonitrobenzene.
Method for preparing indole compounds through catalysis of ionic liquid
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Paragraph 0034-0036, (2018/02/04)
The invention relates to a green synthesis method of one type of indole derivatives. The method is characterized by taking sulfonic acid ionic liquid as a catalyst, taking aliphatic ketone, aromatic ketone and aromatic hydrazine hydrochloride as raw materials, reacting in water, filtering and drying a reaction mixture to obtain indole compounds. The method is simple to operate; the raw materials are low intoxicity and low in costs; the reaction condition is mild; the product is easy to separate; the synthesis process is environmentally-friendly; the indole compounds are high in purity; the catalyst can be directly reused without treatment; the method is green and environmentally-friendly, and is suitable for industrial production.
A Convenient Modification of the Fischer Indole Synthesis with a Solid Acid
Chandrasekhar, Sosale,Mukherjee, Somnath
supporting information, p. 1018 - 1022 (2015/03/30)
(Chemical Equation Presented). A new one-pot version of the titled reaction involves heating a mixture of a carbonyl compound, a phenylhydrazine, and the cation exchange resin Amberlite IR 120 in refluxing ethanol. A variety of enolizable aldehydes, and ketones and several substituted phenylhydrazines could thus be converted to the corresponding indoles in excellent yields (70-88%). Reaction times were typically 6-10 h, with the resin being then filtered off and the product isolated after minimal workup.
Ene-hydrazide from enol triflate for the regioselective Fischer indole synthesis
Lim, Byeong-Yun,Jung, Bo-Eun,Cho, Cheon-Gyu
supporting information, p. 4492 - 4495 (2015/01/09)
Ene-hydrazide prepared from enol triflate undergoes a Fischer indolization reaction to give the corresponding indole with complete regioselectivity. The starting enol triflate is readily accessed in regiochemically defined form from the ketone precursor via various well-established methods. This new protocol was successfully applied to the synthesis of desbromoarborescidine A, a natural β-carboline alkaloid, difficult to prepare with conventional Fischer indole synthesis.
Iodine-catalyzed aromatization of tetrahydrocarbazoles and its utility in the synthesis of glycozoline and murrayafoline A: A combined experimental and computational investigation
Humne, Vivek,Dangat, Yuvraj,Vanka, Kumar,Lokhande, Pradeep
supporting information, p. 4832 - 4836 (2014/07/07)
A new protocol for the aromatization of tetrahydrocarbazoles has been achieved using a catalytic amount of iodine, giving high yields. The role of iodine in the aromatization has been explained by DFT, and its wide scope is extended to the total synthesis of glycozoline and murrayafoline A. This method has proven to be tolerant of a broad range of functional groups. This journal is the Partner Organisations 2014.
A systematic study of two complementary protocols allowing the general, mild and efficient deprotection of N-pivaloylindoles
Ruiz, Míriam,Sánchez, J. Domingo,López-Alvarado, Pilar,Menéndez, J. Carlos
experimental part, p. 705 - 710 (2012/01/06)
Two mild and general protocols for the high-yielding deprotection of indoles and related fused heterocyclic systems are described, involving either hydride transfer from LDA or hydrolysis by the DBU-water system. Both methods were shown to tolerate a wide variety of substituents and functional groups, but the hydrolytic one proved to be particularly general, being compatible with 2-alkyl substituents, aldehydes, ketones, carboxylic acids, halogens, ethers, amides and esters. Yields were normally excellent in both cases, but were usually slightly higher for the reductive method. Taken together, these two protocols provide a general solution to the problem of pivaloyindole deprotection.
Novel SO3H-functionalized ionic liquids catalyzed a simple, green and efficient procedure for Fischer indole synthesis in water under microwave irradiation
Li, Bai Lin,Zhong, Ai Guo,Xu, Dan-Qian
, p. 45 - 50,6 (2020/10/15)
Novel SO3H-functionalized ionic liquids were successfully applied as catalysts for one-pot Fischer indole synthesis under microwave irradiation and in a water medium. Various types of indoles were prepared using single-carbonyl ketones/aldehydes or cyclohexandiones with aryhydrazine hydrochlorides in 86-96% yields in water under microwave irradiation. The indole products could be conveniently separated from the reaction mixture through filtration, and the catalytic system of [(HSO3-p)2im] [CF3SO3]/H2O could be reused directly without any treatment. The entire process is simple, time saving, and environmentally friendly.
