Michael Addition Of Indoles Research Articles

Lignin-Based Catalysts for C-C Bond-Forming Reactions.

Carbon-carbon (C-C) bond formation is the key reaction in organic synthesis to construct the carbon framework of organic molecules. The continuous shift of science and technology toward eco-friendly and sustainable resources and processes has stimulated the development of catalytic processes for C-C bond formation based on the use of renewable resources. In this context, and among other biopolymer-based materials, lignin has attracted scientific attention in the field of catalysis during the last decade, either through its acid form or as a support for metal ions and metal nanoparticles that drive the catalytic activity. Its heterogeneous nature, as well as its facile preparation and low cost, provide competitive advantages over other homogeneous catalysts. In this review, we have summarized a variety of C-C formation reactions, such as condensations, Michael additions of indoles, and Pd-mediated cross-coupling reactions that were successfully carried out in the presence of lignin-based catalysts. These examples also involve the successful recovery and reuse of the catalyst after the reaction.

Michael Addition of Indoles to Enones Catalyzed by a Cationic Iron Salt

AbstractIndoles are one of the most valuable nucleophiles in Michael additions catalyzed by a proper Lewis acid. In this paper, we found that a cationic iron salt is effective to carry out the Michael addition of indoles. β-Mono- and disubstituted enones reacted smoothly with indoles under our conditions. The cationic iron catalyst is very active, and the maximum TON was up to 425. Moreover, cationic iron-catalyzed conditions enabled a chemoselective Michael addition of a substrate possessing both enone and α,β-unsaturated ester moieties.

Green and ecofriendly synthesis of indole‐condensed benzimidazole chalcones in water and their antimicrobial evaluations

AbstractAn ecofriendly synthesis of novel benzimidazole‐substituted indole derivatives catalyzed by ZnO nanoparticles has been developed from simple condensation of acetyl benzimidazole and indole‐3‐carbaldehyde followed by Michael addition of indoles. This ZnO Nano particles (NP)‐catalyzed reaction has been carried out using both step‐wise and one‐pot methods, and both these methods provide excellent yield of product and less reaction time in water. All the synthesized compounds were characterized by Infrared spectroscopy (IR), Proton Nuclear Magnetic Resonance spectroscopy (Proton NMR), Carbon‐13 Proton Nuclear Magnetic Resonance spectroscopy (13C‐NMR), and mass analysis and screened for their antibacterial activity against clinical strains that include Gram‐positive and Gram‐negative bacteria.

Cu(I)-phosphine complex: An efficient catalyst for synthesis of 3-indole derivatives through one-pot MCR under mild conditions

ABSTRACTAn efficient copper (I) halotriphenylphosphine catalyzed one-pot multicomponent reaction (MCR) of 3-substituted indole derivatives has been developed using a variety of aldehydes (aromatic, aliphatic, and heteroaromatic), indole, and active methylene substrates such as malononitrile and ethyl 2-cyano acetate. This reaction proceeds smoothly and obtained good to excellent yields (68–93%) using water as green solvent under ambient conditions. The obtained products were confirmed by 1H, 13C NMR, and mass spectroscopy techniques. The one-pot MCR occurs through formation of Knoevenagel adducts then followed by Michael addition of indole.

A Green and Efficient Michael Addition of Indoles to α, β-unsaturated Electron-deficient Compounds and Synthesis of Bis-indolylmethanes Catalyzed by Gallium Dodecyl Sulfate [Ga(DS)3] in Water

α, β-unsaturated electron-deficient compounds and bis-indolylmethanes were successfully synthesized by gallium dodecyl sul-fate (Ga(DS)3) catalyzed Michael addition using indoles and α, β-unsaturated ketones(or aldehyde) as reactant, respectively. The samples were characterized by 1H NMR (400 MHz), HRMS, and Electrothermal Digital Melting-point. The results showed that the α, β-unsaturated electron-deficient compounds and bis-indolylmethanes could be effectively catalyzed by using Ga(DS)3 to give the corresponding adducts in good to excellent yields in water media.

Water-soluble (salicyladimine)2Cu complex as an efficient and renewable catalyst for Michael addition of indoles to nitroolefins in water

ABSTRACTAn efficient and environmentally friendly protocol has been demonstrated for water-soluble (salicyladimine)2Cu complex-catalyzed Michael addition of indoles to nitroolefins in water at 30 °C. A variety of substituted indoles and β-nitrostyrenes could be worked well to provide the title products in 81–97% yields. Moreover, the catalyst can be reused directly at least for four times without significantly decreasing activity.

Indium(III) Chloride Mediated Michael Addition of Indoles to Ketene S,S-Acetals: Synthesis of Bis- and Tris-indolylketones

Synthesis of Bis- and Tris Indolylketones Bull. Korean Chem. Soc. 2014, Vol. 35, No. 10 2951efficient, selective and mild method for the preparation ofβ,β-bisindolyl-ketones 4, tris-indolylketones 7 and meridi-anin derivatives 8 by treating α-oxoketene dithioacetals withindole in the presence of InCl

Facile and Promising Method for Michael Addition of Indole and Pyrrole to Electron-Deficienttrans-β-Nitroolefins Catalyzed by a Hydrogen Bond Donor Catalyst Feist’s Acid and Preliminary Study of Antimicrobial Activity

The importance of cooperative hydrogen-bonding effects has been demonstrated using novel 3-methylenecyclopropane-1,2-dicarboxylic acid (Feist's acid (FA)) as hydrogen bond donor catalysts for the addition of indole and pyrrole to trans-β-nitrostyrene derivatives. Because of the hydrogen bond donor (HBD) ability, Feist's acid (FA) has been introduced as a new class of hydrogen bond donor catalysts for the activation of nitroolefin towards nucleophilic substitution reaction. It has effectively catalyzed the Michael addition of indoles and pyrrole to β-nitroolefins under optimum reaction condition to furnish the corresponding Michael adducts in good to excellent yields (up to 98%). The method is general, atom-economical, convenient, and eco-friendly and could provide excellent yields and regioselectivities. Some newly synthesized compounds were for examined in vitro antimicrobial activity and their preliminary results are reported.

Synthesis and in vitro cytotoxicity study of 3-(1H-indol-3-yl)-1,3-diphenylpropan-1-ones

A series of 3-(1H-indol-3-yl)-1,3-diphenylpropan-1-ones 3a–l were synthesized in good to excellent yield by Michael addition of indole 1 with α,β-unsaturated ketones 2a–l in presence of indium(III) sulphate (20 mol%). The structure of the title compounds were established by 1H NMR, 13C NMR, mass and elemental analysis. All the synthesized compounds were evaluated for in vitro cytotoxicity against five different cancer cell lines such as ACHN (human kidney adenocarcinoma), Panc1 (pancreatic), Calu1 (lung), H460 (non small cell lung), HCT116 (human colon cancer cell) and MCF10A (normal breast epithelium) using propidium iodide staining assay protocol. The result showed that the compounds 3e and 3l have excellent cytotoxic activity with the IC50 value ranging from 1.4–2.7 to 2.4–3.4 μM, respectively, in comparison with the other compounds, Flavopiridol and Gemcitabine were employed as a positive control. The findings conferred 3-(1H-indol-3-yl)-1,3-diphenylpropan-1-ones seem to be promising candidates for the development of new anticancer drugs.

A ligand-free copper(II)-catalyzed three-component reaction in poly(ethylene glycol) medium: a versatile protocol for the preparation of selected 3-indole derivatives

An efficient and eco-friendly method has been developed for the synthesis of selected 3-indole derivatives via a copper-catalyzed condensation between indole, aldehydes, and malononitrile in polyethylene glycol. The reagent system (PEG solvent plus catalyst) could be recycled up to 5 times for reaction with the same aldehyde and it was used also with at least three different aldehydes successively. This multi-component reaction (MCR) occurs first through Knoevenagel condensation followed by Michael addition of indole.

Iodine in aqueous micellar environment: a mild effective ecofriendly catalytic system for expedient synthesis of bis(indolyl)methanes and 3-substituted indolyl ketones

The three-component condensation reaction of indoles with carbonyl compounds to yield bis(indolyl)methanes has been accomplished with a catalytic amount of iodine (2 mol%) in the presence of sodium dodecylsulfate (SDS) in aqueous solution above its critical micellar concentration (cmc). The surfactant-aided water-compatible Lewis acid catalyst has been found to be efficient for a wide range of carbonyl compounds including aromatic aldehydes bearing electron-releasing and electron-withdrawing groups, α,β-unsaturated aldehydes, heterocyclic aldehydes, cyclic and aromatic ketones with respect to yield, and reaction time. The protocol has been extended to Michael addition of indoles with α,β-unsaturated ketones exclusively yielding 3-substituted indolyl ketones in excellent yields.

Microwave-Promoted Michael Addition of Azaheterocycles to α,β-Unsaturat­ed Esters and Acid under Solvent-Free Conditions

Regioselective Michael addition of N-9 adenine to ethyl acrylate under microwave activation in solid-liquid solvent-free phase-transfer catalysis using TBAB as catalyst and DABCO as base was extended to tert-butyl acrylate and acrylic acid. Under these conditions and in the presence of a catalytic amount of KOH, first Michael addition of indole and indolylmaleimide to acrylates is also reported.

Facile and Efficient Michael Addition of Indole to Nitroolefins Catalyzed by Zn(OAc)2 · 2H2O

The Zn(OAc)22H2O-catalyed Michael addition reaction of indole to electron-deficient nitroolefins to afford the corresponding adducts in good to excellent yields with high selectivity is reported.

Sc(OTf)3: A Highly Efficient and Renewable Catalyst for Michael Addition of Indoles to Nitroolefins in Water

A catalytic amount of scandium trifluoromethanesulfonate [Sc(OTf)3] (2.5 mol%) was used to catalyze the Michael addition of indoles to nitroolefins in water to afford the corresponding 3-alkylated indoles in good to excellent yields. The short reaction times, excellent yields, and renewability of the catalyst are noteworthy.

ChemInform Abstract: The Michael Addition of Indoles and Pyrrole to α‐, β‐Unsaturated Ketones and Double‐Conjugate 1,4‐Addition of Indoles to Symmetric Enones Promoted by Pulverization‐Activation Method and Thia‐Michael Addition Catalyzed by Wet Cyanuric Chloride.

AbstractThe formation of cyanuric acid in wet cyanuric chloride catalyzes the solvent‐free addition of indole, pyrrole, and thiols to α,β‐unsaturated ketones.

Diastereoselective Ruthenium-Catalyzed Michael Addition of Indoles to Hormone Steroids: An Efficient Route to New Indole Derivatives

Diastereoselective conjugate 1,4-addition of indoles to α,β-unsaturated carbonyl compounds (hormone steroids) using Ru(III) as catalyst is reported. It was found that RuCl3·nH2O catalyzes the Michael addition of indoles to hormone steroids, providing new 3-alkylated derivatives in good to excellent yields.

A highly efficient michael addition of indoles to α,β-unsaturated electron-deficient compounds in acidic SDS micellar media

The Michael addition of indoles to α,β-unsaturated electron deficient compounds was catalyzed efficiently at room temperature in acidic micellar solution of sodium dodecyl sulfate (SDS). The substitution on the indole nucleus occurred exclusively at the 3-position in good to excellent yields, and no N-alkylation products were observed.

The Michael addition of indoles and pyrrole to α-, β-unsaturated ketones and double-conjugate 1,4-addition of indoles to symmetric enones promoted by pulverization-activation method and Thia-Michael addition catalyzed by wet cyanuric chloride

A new, facile, and efficient procedure for conjugate addition of indole and pyrrole with Michael acceptors have been developed for pulverization-activation reaction catalyzed by wet cyanuric chloride (2,4,6-trichloro-[1,3,5]-triazine or TCT) through grinding under solvent-free conditions at room temperature. Also, double-conjugate 1,4-addition of indoles to dibenzylidenacetones and conjugate addition of thiols with Michael acceptors using wet-TCT as catalyst is reported.

Montmorillonite K10–Catalyzed Michael Addition of Indoles to Nitroolefins Under Solvent-Free Conditions

Montmorillonite K10 is a very inexpensive and readily available reagent and efficiently catalyzes the Michael addition of indoles to nitroolefins under solvent-free conditions. Reasonable to excellent yields of the desired products were obtained in most cases.

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α, β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety of α, β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl 3 in aqueous media to afford the corresponding products in good to excellent yields.