Efficient Synthesis Of Indoles Research Articles

Palladium-catalyzed synthesis of 2,3-disubstituted indoles via arylation of ortho-alkynylanilines with arylsiloxanes.

In this study, we report the electrophilic cyclization of N,N-dimethyl-o-alkynylanilines with arylsiloxanes in the presence of [Pd(OAc)2] and Ag2O catalytic system, which leads to the efficient synthesis of indoles, similar to the one that is obtained through Larock indole synthesis. A range of aryl(trimethoxy)silanes with EDGs and EWGs were successfully utilized for the synthesis of a diverse variety of substituted indoles via the cleavage of the C-Si bond. This protocol exhibits good functional group tolerance and wide substrate scope to provide 2,3-diaryl-N-methylindoles in 26-88% yields.

Concise and Efficient Synthesis of Indole-Indolone Scaffolds through MeOTf-Induced Annulation of N-(2-Cyanoaryl)indoles.

MeOTf-triggered annulation of N-(2-cyanoaryl)indoles to provide indolo[1,2-a]indol-10-imines and the corresponding indolo[1,2-a]indol-10-ones have been described under metal-free conditions. A variety of functional groups are tolerated in their scaffolds with good to excellent yields. The reaction could be carried to gram scale.

A Green Approach to the Synthesis of Novel Indole Substituted 2-Amino- 4,5-dihydro-3-furancarbonitriles in Water

2-Amino-4,5-dihydro-3-furancarbonitriles (ADFCs) have attracted much attention due to their utility as valuable synthetic intermediates for the preparation of a series of acyclic and cyclic organic compounds. On the other hand, indoles substituted with furans are highly interesting compounds displaying a wide range of biological and pharmaceutical activities. However, to the best of our knowledge, indole substituted 2-amino-4,5-dihydro-3-furancarbonitriles have not been previously reported. A new and efficient synthesis of indole substituted 2-amino-4,5-dihydro-3-furancarbonitriles has been developed in two steps using water as a solvent. The first step of the sequence involves threecomponent reaction of phenylglyoxals, indoles and malononitrile under aqueous and catalyst-free conditions for the synthesis of indole substituted β,β-dicyanoketones. Reduction of the obtained β,β- dicyanoketones with sodium borohydride in water at room temperature afforded the indole substituted 2-amino-4,5-dihydro-3-furancarbonitriles in good yields. Several substituted phenylglyooxals were reacted smoothly with indole or 2-methylindole and malononitrile to give the corresponding indole substituted β,β-dicyanoketones in good yields. Treatment of the obtained β,β-dicyanoketones with sodium borohydride in water furnished exclusively the indole substituted 2-amino-4,5-dihydro-3- furancarbonitriles in good yields. We have developed an efficient straightforward access to indole substituted β,β-dicyanoketones by one-pot three-component reaction of phenylglyoxals, indoles and malononitrile. The synthetic utility of obtained indole substituted β,β-dicyanoketones has been outlined by the preparation of indole substituted 2-amino-4,5-dihydro-3-furancarbonitriles. The advantage of catalyst-free, atom-economical and environmental benignity render it promising methods for preparation of indole substituted 2-amino-4,5-dihydro-3-furancarbonitriles.

An efficient synthesis of indoles via a CuMgAl-LDH-catalyzed cyclization of 2-alkynylsulfonanilides

A highly efficient method for the synthesis of indoles has been successfully developed via a CuMgAl-LDH-catalyzed intramolecular annulation reaction of 2-alkynylsulfonanilides. This CuMgAl-LDH catalyst features facile preparation, recovery, and reuse at least seven times without a marked loss in the catalytic activity, as well as the unique dual activation. Moreover, the crystal structures and Hirshfeld surface analysis of typical indole compounds were also presented.

Mild and efficient synthesis of indoles and isoquinolones via a nickel-catalyzed Larock-type heteroannulation reaction.

A simple and efficient approach for the preparation of substituted indoles and isoquinolones via a nickel-catalyzed Larock-type heteroannulation reaction is reported. This transformation employed air-stable and inexpensive Ni(dppp)Cl2 as a precatalyst and Et3N as a mild base. Moreover, the reaction occurs efficiently under mild conditions, and a wide range of substituted indoles and isoquinolones bearing various functional groups are obtained in moderate to excellent yields.

SN1-Type Alkylation of N-Heteroaromatics with Alcohols.

The organocatalytic alkylation of 2-methyl-N-heteroaromatics with alcohols has been achieved via SN1-type C(sp3)-H functionalization, providing a green and efficient synthesis of indole and ferrocene-functionalized N-heteroaromatics in high yields.

Iridium(iii)- and rhodium(iii)-catalyzed coupling of anilines with α-diazoesters via chelation-assisted C–H activation

Ir(iii) catalysts can catalyze the efficient synthesis of indoles via C–H activation of anilines in the coupling with α-diazo β-ketoesters.

ChemInform Abstract: Efficient Synthesis of Indoles from 2‐Alkynylaniline Derivatives in Water Using a Recyclable Copper Catalyst System.

AbstractA recyclable catalyst system consisting of CuI, Bu4NBr, and polystyrene‐supported perruthenate effectively promotes the cyclization reaction of ethynyl‐N‐sulfonylanilides to indoles in water.

Efficient synthesis of indoles from 2-alkynylaniline derivatives in water using a recyclable copper catalyst system

A recyclable, effective CuI/PSP (polystyrene-supported pyrrole-2-carbohydrazide) catalyst system was established, with which a variety of N-(2-ethynylphenyl)-sulfonamides, even those with bulky substituents on the aromatic ring, have been smoothly cyclized to indoles in water with excellent yields.

The Synthesis and Light Absorption Behaviour of Novel Coumarin Chromophores

The synthetic route to coumarin systems is well established and one approach of particular interest leads to the intermediate 7-diethylamino-3-formylcoumarin. A combination of the N,N-diethylamino-coumarin donor with a wide range of acceptor groups of varying electron withdrawing strength should permit the synthesis of a series of extended coumarin dyes with absorption maxima range from 500 to 600 nm, or even beyond. In this communication, a novel efficient synthesis of indoles, benzothiazole and benzoxazole based on coumarin chromophores were achieved and the coloristic and fluorophoric properties of these chromophores were studied.

General and Efficient Synthesis of Indoles through Triazene‐Directed C–H Annulation

The first general protocol for the synthesis of unprotected indoles via the title reaction is presented.

General and Efficient Synthesis of Indoles through Triazene‐Directed C–H Annulation

Ungeschützte Indole werden mithilfe der im Titel genannten Methode hergestellt, wobei verschiedene Alkine verwendet werden können. Aryl-Alkyl- und Alkyl-Alkyl-disubstituierte Acetylene führten zu ausgezeichneten Regioselektivitäten. Die Reaktion enthält eine 1,2-Rhodium-Wanderung und eine durch Ringkontraktion ausgelöste N-N-Bindungsspaltung. Die Reaktionsprodukte können schnell zu funktionellen Molekülen umgesetzt werden. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

SO<sub>3</sub>H-Functionalized Ionic Liquids-Catalyzed Facile and Efficient Procedure for Fischer Indole Synthesis under Ultrasound Irradiation

A facile and efficient synthesis of indole has been developed using ketones or cyclohexandiones with aryhydrazine hydrochlorides in 85% to 95% yields in water under ultrasound irradiation in the presence of Novel SO3H-functionalized ionic liquids (ILs) catalyst. Simple work-up procedure, environmentally friendly, inexpensive and non-toxic catalyst, shorter reaction times along with excellent product yields are the significant features of this practical method.

One-Pot Synthesis of Indoles and N-Fused Indoles from Nitriles

Reported is a moderately efficient synthesis of indoles 3 and N-fused indoles 5 by the reaction of nitriles 1 and 4 with ethyl (2-bromophenyl)-α-bromoacetate 2. The synthesis involves a two-step, one-pot sequence in which nitriles 1 or 4 initially undergo a Blaise reaction with a Reformatsky reagent generated in situ from 2 and zinc metal, followed by intramolecular C-N coupling to form the indole derivatives 3 and 5. Both aliphatic and aromatic nitriles are suitable for the reaction and in case of the latter, both EDG and EWG are tolerated.

A facile synthesis of indole–furan conjugates via integration of convergent and linear domino reactions

The convergent and linear domino reactions have been first integrated, for the first time, to provide an efficient synthesis of indole–furan conjugates from indoles, methyl ketones, and 1,3-dicarbonyl compounds.

ChemInform Abstract: Palladium‐Free Zinc‐Mediated Hydroamination of Alkynes: Efficient Synthesis of Indoles from 2‐Alkynylaniline Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Efficient Synthesis of Indoles and Benzo[b]furans via [3,3]‐Sigmatropic Rearrangement of N‐Trifluoroacetyl Enehydrazines and Enehydroxylamines

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Palladium-free zinc-mediated hydroamination of alkynes: efficient synthesis of indoles from 2-akynylaniline derivatives

Reaction of 2-phenylethynyl N-tosylanilide prepared by Pd-free procedure with ZnBr 2 (3 equiv) in refluxing toluene gave N-tosyl-2-phenylindole in 93% yield. Treatment of 2-phenylethynylaniline with ZnBr 2 (1 equiv) in refluxing toluene resulted in the formation of 2-phenylindole in 91% yield. Catalytic ZnBr 2 (0.05 equiv) effectively reacted with 2-alkynylanilines to afford 2-substituted indoles in high yields. Thus, complete Pd-free zinc catalyzed hydroamination of 2-alkynylanilines was achieved.

Efficient Synthesis of Indoles and Benzo[b]furans via [3,3]-Sigmatropic Rearrangement of N-Trifluoroacetylenehydrazines and Enehydroxylamines

- This review summarizes an efficient synthesis of benzo[b]furans and indoles via [3,3]-sigmatropic rearrangements of N-trifluoroacetyl enehydroxylamines and enehydrazines, which were triggered by acylation of oxime ethers and hydrazines. TFAA and TFAT-DMAP have been proved to be the best reagent to induce [3,3]-sigmatropic rearrangement for the synthesis of benzo[b]furans and indoles. This method was successfully applied to the short synthesis of natural products.

Chemistry of Aminophenols. Part 2. A General and Efficient Synthesis of Indoles Possessing a Nitrogen Substituent at the C4, C5, C6, and C7 Positions.

AbstractFor Abstract see ChemInform Abstract in Full Text.