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Journal ArticleDOI

Synthesis of 3-substituted indoles promoted by pulverization-activation method catalyzed by Bi(NO3)3·5H2O

TL;DR: In this paper, a new, facile, efficient, "green" and chemoselective procedure for the synthesis of indole derivatives has been developed with pulverization-activation method catalyzed by Bi(NO3)3·5H2O (PAMC-Bi(NO 3)3 ·5H 2O) through grinding of indoles with aldehydes or Michael acceptors.
About: This article is published in Journal of Heterocyclic Chemistry.The article was published on 2008-03-01. It has received 37 citations till now. The article focuses on the topics: Indole test & Catalysis.
Citations
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Journal ArticleDOI
TL;DR: This review article summarizes the applications of bismuth(III) compounds in organic synthesis since 2002 and is largely organized by the reaction type although some reactions can be placed in multiple sections.
Abstract: This review article summarizes the applications of bismuth(III) compounds in organic synthesis since 2002. Although there are an increasing number of reports on applications of bismuth(III) salts in polymerization reactions, and their importance is acknowledged, they are not included in this review. This review is largely organized by the reaction type although some reactions can clearly be placed in multiple sections. While every effort has been made to include all relevant reports in this field, any omission is inadvertent and we apologize in advance for the same (358 references).

219 citations

Journal ArticleDOI
TL;DR: Glycerol was used, for the first time, as a green and effective promoting medium for electrophilic activation of aldehydes, and with which, a catalyst-free system for some reactions that conventionally carried out using acid catalysts, such as synthesis of di(indolyl)methanes, 3,4,5,6,7,9-hexahydro-9-aryl-1H-xanthene-1,8(2H)-dione and 1-oxo-hexaphroxanthenes, was developed

112 citations

Journal ArticleDOI
TL;DR: A simple, clean, and highly efficient green protocol has been developed for synthesis of bis(indolyl), di(bis-indolyL), and tris-indolel methanes by the reaction of indole with aldehydes and ketones in the presence of oxalic acid dihydrate.
Abstract: A simple, clean, and highly efficient green protocol has been developed for synthesis of bis(indolyl), di(bis-indolyl), and tris-indolyl methanes by the reaction of indole with aldehydes and ketones irn the presence of oxalic acid dihydrate [(CO2H)2·2H2O] and N-cetyl-N, N, N-trimethylammonium bromide (CTAB) in water. Also, tri(bis-indolyl) and tetra(bis-indolyl)methanes as new bis(indolyl)methanes were prepared under thermal conditions.

60 citations

Journal ArticleDOI
TL;DR: The simplicity and easy operational methodology using a small amount of commercially available AgOTf, one of the lowest catalytic charge used in this process to date, makes this procedure an alternative approach for this interesting and appealing reaction.
Abstract: A novel approach for the catalyzed formation of bisindolylmethane derivatives (BIMs) is described. This methodology is the unique example where AgOTf has been successfully used for the activation of aldehydes, giving easy access to a broad range of bisindolyl derivatives with excellent results. Moreover, the simplicity and easy operational methodology using a small amount of commercially available AgOTf (1–3 mol %), one of the lowest catalytic charge used in this process to date, makes this procedure an alternative approach for this interesting and appealing reaction.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a reusable nano-TiO2/SiO2 catalyst for the condensation reaction of indoles with isatins to afford the corresponding bis(indolyl)oxindoles at 50°C under solvent-free conditions was presented.

29 citations

References
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Journal ArticleDOI
TL;DR: Bismuth nitrate-catalyzed versatile Michael reaction was developed to reduce the complications that characterize the current standard Michael reaction and used for facile preparation of organic compounds of widely different structures.
Abstract: Bismuth nitrate-catalyzed versatile Michael reaction was developed to reduce the complications that characterize the current standard Michael reaction and used for facile preparation of organic compounds of widely different structures. For example, several substituted amines, imidazoles, thio compounds, indoles, and carbamates were prepared at room temperature by following this method. In contrast with the existing methods using many acidic catalysts, this method is very general, simple, high-yielding, environmentally friendly, and oxygen and moisture tolerant. However, the promoting role of bismuth nitrate in this reaction is not understood at this time.

365 citations

Journal ArticleDOI
TL;DR: Highly rapid and efficient electrophilic substitution reactions of indoles with various aldehydes and ketones were carried out using I2 in CH3CN to afford the corresponding bis(indolyl)methanes in excellent yields.

273 citations

Journal ArticleDOI
TL;DR: With the optimized atom-efficient protocol, several polyfunctionalized alpha-silyloxy cyanohydrins were synthesized in good to excellent yields and a notable level of simple 1,3-diastereoselection was recorded in the case of 2-cyclohexen-1-one 2c.
Abstract: Low sensitivity toward traces of moisture and high tolerance of different functional groups make indium tribromide suitable for carrying out multistep synthetic sequences. In particular, we have realized a 1,4-conjugated addition of indoles/thiols to α,β-unsaturated ketones mediated by a catalytic amount (10 mol %) of InBr3 obtaining the desired β-substituted ketones in good yields. The Lewis acidity of indium salts was not affected by coordinating and acid nucleophiles; therefore, the subsequent catalytic 1,2-addition of Me3SiCN to carbonyl compounds can be performed in one pot. With the optimized atom-efficient protocol, several polyfunctionalized α-silyloxy cyanohydrins were synthesized in good to excellent yields (up to 97%) and a notable level of simple 1,3-diastereoselection (up to 84:16) was recorded in the case of 2-cyclohexen-1-one 2c.

228 citations

Journal ArticleDOI
TL;DR: The indole derivatives 2,2-bis(3,3'-indolyl)propionic acid (1); 1,1,1,-tris(3-3-,3"-indolyls)ethane (2); and 2-2-isocaproic acid (3) were isolated from solvent extracts of indole-supplemented supernatants of Escherichia coli and corynebacteria.
Abstract: The novel indole derivatives 2,2-bis(3,3'-indolyl)propionic acid (1); 1,1,1,-tris(3,3',3"-indolyl)ethane (2); and 2,2-bis(3, 3'-indolyl)isocaproic acid (3) were isolated from solvent extracts of indole-supplemented supernatants of Escherichia coli and corynebacteria. The compounds were also obtained by chemical synthesis: compounds 1 and 2 from indole and pyruvic acid and compound 3 from indole and alpha-ketoisocaproic acid, following incubation at 37 degrees C in aqueous medium. Tryptophan and pyruvic acid gave the novel 2-(2-tryptophanyl)lactic acid (4). The condensation reaction between indoles and alpha-keto acids was of general nature, and the mild reaction conditions suggested it may proceed in vivo. Examples for endogenous occurrence may be the neuro-degenerative diseases phenylketonuria and maple syrup urine disease, both characterized by elevated blood levels of alpha-keto acids.

223 citations

Journal ArticleDOI
TL;DR: In this paper, Lanthanide triflates were found to be effective catalysts for reactions of indoles with aldehydes or ketones in aqueous solution.

208 citations