19013-49-1Relevant academic research and scientific papers
One-pot, three-component Fischer indolisation-N-alkylation for rapid synthesis of 1,2,3-trisubstituted indoles
Hughes-Whiffing, Christopher A.,Perry, Alexis
supporting information, p. 627 - 634 (2021/02/06)
A one-pot, three-component protocol for the synthesis of 1,2,3-trisubstituted indoles has been developed, based upon a Fischer indolisation-indoleN-alkylation sequence. This procedure is very rapid (total reaction time under 30 minutes), operationally straightforward, generally high yielding and draws upon readily available building blocks (aryl hydrazines, ketones, alkyl halides) to generate densely substituted indole products. We have demonstrated the utility of this process in the synthesis of 23 indoles, benzoindoles and tetrahydrocarbazoles bearing varied and useful functionality.
Allylic and Allenylic Dearomatization of Indoles Promoted by Graphene Oxide by Covalent Grafting Activation Mode
Lombardi, Lorenzo,Bellini, Daniele,Bottoni, Andrea,Calvaresi, Matteo,Monari, Magda,Kovtun, Alessandro,Palermo, Vincenzo,Melucci, Manuela,Bandini, Marco
, p. 10427 - 10432 (2020/07/24)
The site-selective allylative and allenylative dearomatization of indoles with alcohols was performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt percent loading) as the promoter. Metal-free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 °C, 6 h), broad substrate scope (33 examples, yield up to 92 percent) and excellent site- and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst through simple acidic treatment was also documented.
Soluble asphaltene oxide: A homogeneous carbocatalyst that promotes synthetic transformations
Bielawski, Christopher W.,Jung, Hyosic
, p. 15598 - 15603 (2020/05/05)
Carbocatalysts, materials which are predominantly composed of carbon and catalyze the synthesis of organic or inorganic compounds, are promising alternatives to metal-based analogues. Even though current carbocatalysts have been successfully employed in a broad range of synthetic transformations, they suffer from a number of drawbacks in part due to their heterogeneous nature. For example, the insolubility of prototypical carbocatalysts, such as graphene oxide (GO), may restrict access to catalytically-active sites in a manner that limits performance and/or challenges optimization. Herein we describe the preparation and utilization of soluble asphaltene oxide (sAO), which is a novel material that is composed of oxidized polycyclic aromatic hydrocarbons and is soluble in a wide range of organic solvents as well as in aqueous media. sAO promotes an array of synthetically useful transformations, including esterifications, cyclizations, multicomponent reactions, and cationic polymerizations. In many cases, sAO was found to exhibit higher catalytic activities than its heterogeneous analogues and was repeatedly and conveniently recycled, features that were attributed to its ability to form homogeneous phases.
Supported dual-acidic 1,3-disulfoimidazolium chlorozincate@HZSM-5 as a promising heterogeneous catalyst for synthesis of indole derivatives
Saikia, Susmita,Puri, Krishna,Borah, Ruli
, (2019/02/03)
HZSM-5-supported Br?nsted and Lewis acidic ionic solid 1,3-disulfoimidazolium chlorozincate materials ([dsim]2[ZnCl4]@HZSM-5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt-loaded HZSM-5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X-ray diffraction and inductively coupled plasma optical emission spectrometric techniques.
Asymmetric N-Hydroxyalkylation of Indoles with Ethyl Glyoxalates Catalyzed by a Chiral Phosphoric Acid: Highly Enantioselective Synthesis of Chiral N,O-Aminal Indole Derivatives
Wang, Le,Zhou, Jia,Ding, Tong-Mei,Yan, Zhi-Qiang,Hou, Si-Hua,Zhu, Guo-Dong,Zhang, Shu-Yu
supporting information, p. 2795 - 2799 (2019/04/30)
A method of SPINOL-derived chiral phosphoric acid catalyzed asymmetric intermolecular N-hydroxyalkylation of multisubstituted indoles with ethyl glyoxalates is described in this report. This protocol provides an alternative, convenient, and direct strategy for efficient access to structurally unique α-chiral indole N,O-acyclic aminals with a broad substrate scope and good to excellent enantioselectivities. The synthetic utility of this methodology is illustrated by a gram-scale experiment and the subsequent efficient synthesis of more complex chiral N,O-aminal indole derivatives.
Water-Soluble Hypervalent Iodine(III) Having an I-N Bond. A Reagent for the Synthesis of Indoles
Xia, Hai-Dong,Zhang, Yan-Dong,Wang, Yan-Hui,Zhang, Chi
, p. 4052 - 4056 (2018/07/15)
A readily accessible and bench-stable water-soluble hypervalent iodine(III) reagent (phenyliodonio)sulfamate (PISA) with an I-N bond was synthesized, and its structure was characterized by X-ray crystallography. With PISA, various indoles were synthesized via C-H amination of 2-alkenylanilines involving an aryl migration/intramolecular cyclization cascade with excellent regioselectivity in aqueous CH3CN. Notably, using this new method as the key step, not only two drug molecules, indometacin and zidometacin, but also another bioactive molecule, pravadoline, were synthesized.
Method for preparing indole compounds through catalysis of ionic liquid
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Paragraph 0028-0030, (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.
Palladium-Catalyzed Dearomative Allylic Alkylation of Indoles with Alkynes to Synthesize Indolenines with C3-Quarternary Centers
Gao, Shang,Wu, Zijun,Fang, Xinxin,Lin, Aijun,Yao, Hequan
supporting information, p. 3906 - 3909 (2016/08/16)
A palladium-catalyzed dearomative allylic alkylation of indoles with alkynes to construct indolenines with C3-quarternary centers was reported. The in situ formed arylallene intermediate omitted the need to install leaving groups on the allylic compounds and employ extra oxidants to oxidize the allylic C-H bonds. The reaction exhibited good functional group tolerance and high atom economy. Moreover, the reaction was further expanded to synthesize pyrroloindolines and furanoindolines.
Catalytic α-Arylation of Imines Leading to N-Unprotected Indoles and Azaindoles
Marelli, Enrico,Corpet, Martin,Minenkov, Yury,Neyyappadath, Rifahath M.,Bismuto, Alessandro,Buccolini, Giulia,Curcio, Massimiliano,Cavallo, Luigi,Nolan, Steven P.
, p. 2930 - 2938 (2016/07/06)
A palladium N-heterocyclic carbene catalyzed methodology for the synthesis of substituted, N-unprotected indoles and azaindoles is reported. The protocol permits access to various, highly substituted members of these classes of compounds. Although two possible reaction pathways (deprotonative and Heck-like) can be proposed, control experiments, supported by computational studies, point toward a deprotonative mechanism being operative.
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.
