- Convenient procedure for dethioketalisation in nitrogen heterocycles
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Regeneration of carbonyl compounds from the corresponding thioketals in nitrogen heterocycles have been effected using Dowex 50W acidic catalyst in reasonable yields.
- Giri,Sankar
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Read Online
- Microwave-assisted Friedel-Crafts acylation of indole with acetic anhydride over tungstophosphoric acid modified Hβ zeolite
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Friedel-Crafts acylation of indole with acetic anhydride has been carried out over zeolites under microwave and conventional heating, respectively. A tungstophosphoric acid modified Hβ (PW-Hβ) zeolite showed better catalytic performance than parent Hβ zeolite due to its higher amount of strongly acidic sites and lower amount of Lewis acid sites, confirmed from NH3 temperature-programmed desorption (NH3-TPD) and Fourier Transform Infrared Spectrometer after adsorption of pyridine (Py-IR). Particularly, microwave radiation was found to make this transformation not only more efficient but also selective to 3-acetylindole compared with conventional heating. Furthermore, PW-Hβ has shown good stability in this reaction.
- Bai, Guoyi,Li, Tianyu,Yang, Yonghui,Zhang, Huanhuan,Lan, Xingwang,Li, Fei,Han, Jie,Ma, Zheng,Chen, Qingzhi,Chen, Guofeng
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Read Online
- Overcoming Electron-Withdrawing and Product-Inhibition Effects by Organocatalytic Aerobic Oxidation of Alkylpyridines and Related Alkylheteroarenes to Ketones
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An organocatalyzed aerobic benzylic C-H oxidation of alkyl and aryl heterocycles has been developed. This transition metal-free method is able to overcome the electron-withdrawing effect as well as product-inhibition effects in heterobenzylic radical oxidation. A variety of ketones bearing N-heterocyclic groups could be prepared under relatively mild conditions with moderate to high yields.
- Wang, Hua,Liu, Jie,Qu, Jian-Ping,Kang, Yan-Biao
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p. 3942 - 3948
(2020/03/23)
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- Cobalt-Catalyzed Regioselective Direct C-4 Alkenylation of 3-Acetylindole with Michael Acceptors Using a Weakly Coordinating Functional Group
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Herein, we disclosed the first report on the selective C(4)-H functionalization of 3-acetylindole derivatives using first-row transition metal cobalt where an acetyl group is acting as a weakly coordinating directing group. Selective C(4)-H functionalization has been achieved using diverse Michael acceptors (acrylate and maleimide) simply by switching the additive from copper acetate to silver carbonate. Further the formation of a cobaltacycle intermediate was also detected through HRMS for mechanistic insight.
- Banjare, Shyam Kumar,Nanda, Tanmayee,Ravikumar
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supporting information
p. 8138 - 8143
(2019/10/14)
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- Na 2 CO 3-Catalyzed N-Acylation of Indoles with Alkenyl Carboxylates
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The N-acylation of indoles has been accomplished via inorganic base catalysis. It provided an efficient and simple catalysis system for the preparation of N-acylindoles with alkenyl carboxylates as acylating agents. A broad variety of indoles undergo the smooth N-acylation using Na 2 CO 3 as catalyst in MeCN at 120? °C to give the corresponding N-acylindoles in good to excellent yields.
- Zhou, Xiao-Yu,Chen, Xia
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supporting information
p. 516 - 521
(2019/01/10)
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- Based on carboxylic acid allyl ester as the acylation reagent N - acyl indoles preparation method (by machine translation)
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Based on carboxylic acid allyl ester as the acylation reagent N - acyl indoles preparation method, which belongs to the medical and chemical intermediates and related chemical technical field. This method uses the indole compounds and carboxylic acid allyl ester as the raw material, in the catalysis of alkali, realizes the N - acyl indoles of green, efficient synthesis. The method has high selectivity, mild reaction conditions, functional group compatibility is good, wide substrate range, environment-friendly and the like. Because the N - acyl indoles is an important organic synthetic intermediates, in organic synthesis and in the field of pharmacy has very wide application, therefore, the invention has great application value and social and economic benefits. (by machine translation)
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Paragraph 0041-0043
(2018/12/02)
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- Hydrogen bond donor solvents enabled metal and halogen-free Friedel–Crafts acylations with virtually no waste stream
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We have developed a metal and halogen-free Friedel–Crafts acylation protocol with virtually no waste stream generation. We propose a hydrogen bonding donor solvent will form a hydrogen bonding network and may provide significant rate enhancement for Friedel–Crafts reactions. Trifluoroacetic acid is one of the strongest H-bond donor solvents, which is also volatile and can be easily recovered by distillation without need for reaction workup. Our protocol is a ‘green’ Friedel–Crafts acylation process: 1) the catalyst can be recovered and reused; 2) using halogen free starting material (carboxylic acids anhydride or carboxylic acids); 3) no need for aqueous reaction work-up; 4) minimum or no waste steam generation.
- Liu, Guangchang,Xu, Bo
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supporting information
p. 869 - 872
(2018/02/09)
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- Three-Component Coupling-Oxidative Amidation-Heterocycloannulation: Synthesis of the Indole Alkaloids Hamacanthin A and trans -2,5-Bis(3′-Indolyl)piperazine
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Concise and highly convergent syntheses of antifungal marine bis(indole) alkaloids, hamacanthin A and trans-2,5-bis(3′-indolyl)piperazine is described. The total synthesis of hamacanthin A is accomplished via the oxidative amidation-chemoselective heterocycloannulation of 2,2-dibromo-1-(1H-indol-3-yl)ethanone with 1-(1H-indol-3-yl)ethane-1,2-diamine. The reduction of desbromo hamacanthin with aluminum borohydride afforded the alkaloid trans-2,5-bis(3′-indolyl)piperazine. Two novel and convenient protocols for the synthesis of indolyl-1,2-diaminoethane are also developed in moderate to good yields.
- Srinivasan, A. Kaliyaperumal,Banerjee, Shyamapada,Pachore, Sharad S.,Syam Kumar
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p. 1057 - 1064
(2017/05/19)
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- One-Step Dual Template Mediated Synthesis of Nanocrystalline Zeolites of Different Framework Structures
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A novel, dual template mediated, one-step direct synthesis route is reported here for the preparation of nanocrystalline zeolites of different framework structures (such as ZSM-5, mordenite, and sodalite). In this synthesis strategy, a suitably designed dicationic/tetra-cationic soft template was used along with a conventional zeolite structure director to obtain nanocrystalline zeolites with nanosheet morphology. Nanocrystalline zeolites exhibited large surface area, pore volume, and intercrystalline mesopores. The long hydrophobic chain containing a multiammonium template cooperatively participates in the zeolite crystallization process along with a conventional microporous zeolite structure director to form the ultrathin microporous zeolite framework, while the hydrophobic interaction between the long chains restricted the excessive growth of zeolites and induced the formation of intercrystalline mesopores. Nanocrystalline zeolites exhibited exceptionally high activity in the acid-catalyzed reactions involving large molecules when compared with conventional zeolites. This synthesis strategy can be extended for the preparation of zeolites of different framework structures or other porous materials in the future.
- Rani, Poonam,Srivastava, Rajendra,Satpati, Biswarup
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p. 3323 - 3333
(2016/06/14)
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- Synthesis of industrially important aromatic and heterocyclic ketones using hierarchical ZSM-5 and Beta zeolites
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Hierarchical ZSM-5 and Beta zeolites were investigated in the synthesis of wide range of industrially important aromatic/heterocyclic ketones by Friedel-Crafts acylation and benzoylation reactions. For comparative study, conventional ZSM-5 and Beta, and amorphous mesoporous Al-MCM-41 were investigated. Hierarchical zeolites were prepared by multi-ammonium structure directing agents whereas conventional zeolites were prepared by mono-ammonium structure directing agents. Among the catalysts investigated in this study, hierarchical Beta exhibited the highest reactant conversion in the acylation and benzoylation reactions. In this study, the systematic assessment of the catalytic activity of acid catalysts for wide range of aromatic and heterocyclic compounds is shown under one umbrella. To the best of our knowledge, these reactions over hierarchical zeolites (ZSM-5 and Beta) are reported here for the first time. Structure activity relationship is explained based on the physico-chemical properties, molecular size, reactivity of reactants, and reaction mechanism. Catalysts can be easily recovered and reused with negligible loss in the catalytic activity.
- Kore, Rajkumar,Srivastava, Rajendra,Satpati, Biswarup
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p. 129 - 141
(2015/09/28)
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- Regioselective hydroarylation reactions of C3 electrophilic N-acetylindoles activated by FeCl3: An entry to 3-(Hetero)arylindolines
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A method for the direct and rare umpolung of the 3 position of indoles is reported. The activation of N-acetylindole with iron(III) chloride allows the C-H addition of aromatic and heteroaromatic substrates to the C2-C3 double bond of the indole nucleus to generate a quaternary center at C3 and leads regioselectively to 3-arylindolines. Optimization, scope (50 examples), practicability (gram scale, air atmosphere, room temperature), and mechanistic insights of this process are presented. Synthetic transformations of the indoline products into drug-like compounds are also described.
- Beaud, Rodolphe,Guillot, Regis,Kouklovsky, Cyrille,Vincent, Guillaume
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supporting information
p. 7492 - 7500
(2014/06/23)
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- Electrosynthesis of fluorinated indole derivatives
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Anodic fluorination of various N-acetyl-3-substituted indole derivatives was successfully carried out in Et4NF-4HF/MeCN to provide the corresponding trans-2,3-difluoro-2,3-dihydroindoles exclusively or selectively. Treatment of difluorinated products with a base provided monofluoroindole derivatives or monofluoroindoline derivative depending on the substituents at the 3-position.
- Yin, Bin,Wang, Laihao,Inagi, Shinsuke,Fuchigami, Toshio
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experimental part
p. 6820 - 6825
(2010/09/17)
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- Formation of indole nucleus via intramolecular cyclization of aminophenylpropenyltriphenylphosphonium salts with one-carbon degradation
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Treatment of 3-(2-aminophenyl)-2-propenyltriphenylphosphonium bromide with acid anhydride and tertiary amine affords 1,3-diacylindoles in yields ranging from 22 to 64%. A plausible mechanism of this new cyclization reaction is described.
- Taira, Shin'Ichi,Danjo, Hiroshi,Imamoto, Tsuneo
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p. 8893 - 8896
(2007/10/03)
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- Efficient and simple methods for the introduction of the sulfonyl, acyl and alkyl protecting groups on the nitrogen of indole and its derivatives
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The benzenesulfonylation, acetylation, methylation and benzylation at the 1 position of indole and its derivatives with bases such as NaOH, KOH and NEt3 are presented. By using weaker bases than the traditional ones (BuLi, NaNH2, etc.), the process is simpler, more general and leads to the products in 80-100% yields. The chemoselectivity in compounds bearing more than one nitrogen is also demonstrated.
- Ottoni, Olivia,Cruz, Rosimeire,Alves, Robledo
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p. 13915 - 13928
(2007/10/03)
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- FORMATION OF 6-ACYLINDOLES FROM 1-ACYLINDOLES
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1-Acylindoles react regioselectively with α-halogenoacyl chloride in the presence of aluminum chloride to produce 1-acyl-6-halogenoacylindoles in excellent yields.
- Nakatsuka, Shin-ishi,Teranishi, Katsunori,Goto, Toshio
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p. 2699 - 2700
(2007/10/02)
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- INDOLE DERIVATIVES. 131.* REACTION OF 1-ACYLINDOLES WITH ACETYLCHLORIDE AND CHLOROACETYLCHLORIDE UNDER FRIEDEL-CRAFTS CONDITIONS
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Acylation of 1-acylindoles by acetylchloride and chloroacetylchloride in the presence of aluminium chloride leads to formation of 3-acetyl and 6-chloroacetyl-1-acylindoles, respectively.
- Shner, V.F.,Sladkova, T.N.,Turchin, K.F.,Suvorov, N.N.
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p. 272 - 274
(2007/10/02)
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- Simple N-Alkylation and N-Acylation of 3-Acetylindole and 3-Indolecarbaldehyde
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Using lithium cyanide a simple method for the transformation of 3-acetylindole into the N-alkyl, N-acyl, and N-p-toluenesulfonyl derivatives in good yield is reported. 3-Indolecarbaldehyde is also N-alkylated by the same procedure.
- Kurihara, Takushi,Fujimoto, Toshiro,Harusawa, Shinya,Yoneda, Ryuji
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p. 396 - 397
(2007/10/02)
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- Electrophilic Substitution in Indoles. Part 13. The Synthesis and Rearrangement of 2-Deuteriospiro
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2-Deuterioindole was prepared from N-phenylsulphonylindole by lithiation, quenching with D2O, and hydrolysis.Treatment of the 2-deuterioindole Grignard reagent with succinic anhydride gave 4-(indol-3-yl)-4-oxobutanoic acid with partial loss of the deuterium from the 2-position. 2,3-Dideuterioindole (prepared by acid-catalysed deuteration of 2-deuterioindole) when treated in the same way, gave the indolyl oxobutanoic acid, 92 percent deuteriated at the indolyl 2-position.Reduction to the deuterioindolylbutanol and treatment of its toluene-p-sulphonate with potassium t-butoxide give 2-deuterio-spiro which was 88 percent deuteriated at the 2-position.The kinetics of the acid-catalysed rearrangement of the deuterioindolenine and its non-deuteriated analogue were measured and the ratio kH/kD of the pseudo-first-order rate constants was found to be 1.08, showing that the isotope effect was very small.
- Ibaceta-Lizana, Juana S. L.,Jackson, Anthony H.,Prasitpan, Noojare,Shannon, Patrick V. R.
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p. 1221 - 1226
(2007/10/02)
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