This work presents a new greener alternative for biocondensation of aldehydes and indoles for the synthesis of bis- and tris(indolyl)methanes catalyzed by lemon juice (Citrus limon) in good yields under ultrasound irr...This work presents a new greener alternative for biocondensation of aldehydes and indoles for the synthesis of bis- and tris(indolyl)methanes catalyzed by lemon juice (Citrus limon) in good yields under ultrasound irradiation in aqueous ethanol. Various substituted aldehydes with indoles under this reaction condition are elucidated. Also, tetraindolyl compounds were prepared using terephthaldialdehyde by following the same protocol. This method is an environmentally benign, efficient reaction, which requires shorter reaction time and simple experimental and work-up procedures.展开更多
A global and local charge transfer partitioning model,based on the cornerstone theory developed by Robert G.Parr and Robert G.Pearson,which introduces two charge transfer channels(one for accepting electrons(electroph...A global and local charge transfer partitioning model,based on the cornerstone theory developed by Robert G.Parr and Robert G.Pearson,which introduces two charge transfer channels(one for accepting electrons(electrophilic) and another for donating(nucleophilic)),is applied to the reaction of a set of indoles with 4,6-dinitrobenzofuroxan.The global analysis indicates that the prevalent electron transfer mechanism in the reaction is a nucleophilic one on the indoles,i.e.,the indoles under consideration transfer electrons to 4,6-dinitrobenzofuroxan.Evaluating the reactivity descriptorswith exchange-correlation functionals including exact exchange(global hybrids) yields slightly better correlations than those obtained with generalized gradient-approximated functionals;however,the trends are preserved.Comparing the trend obtained with the number of electrons donated by the indoles,and predicted by the partitioning model,with that observed experimentally based on the measured rate constants,we propose that the number of electrons transferred through this channel can be used as a nucleophilicity scale to order the reactivity of indoles towards 4,6-dinitrobenzofuroxan.This approach to obtain reactivity scales has the advantage of depending on the intrinsic properties of the two reacting species;therefore,it opens the possibility that the same group of molecules may show different reactivity trends depending on the species with which they are reacting.The local model allows systematic incorporation of the reactive atoms based on the their decreasing condensed Fukui functions,and the correlations obtained by increasing the number of reactive atoms participating in the local analysis of the transferred nucleophilic charge improve,reaching an optimal correlation,which in the present case indicates keeping three atoms from the indoles and two from 4,6-dinitrobenzofuroxan.The atoms selected by this procedure provide valuable information about the local reactivity of the indoles.We further show that this information about the most reactive atoms on each reactant,combined with the spatial distribution of the nucleophilic and electrophilic Fukui functions of both reactants,allows one to propose non-trivial candidates of starting geometries for the search of the transition state structures present in these reactions.展开更多
A variety of indole derivatives were designed, synthesized and preliminarily evaluated for their in vitro cytotoxic activity in the A431 and H460 cell lines. All the compounds examined conferred unusual potency in a t...A variety of indole derivatives were designed, synthesized and preliminarily evaluated for their in vitro cytotoxic activity in the A431 and H460 cell lines. All the compounds examined conferred unusual potency in a tumor cell cytotoxicity assay. The findings showed the indole derivatives would be a promising candidate for the development of new anticancer agents.展开更多
A new facile, efficient and very mild entry to the synthesis of 3-（1H-indol-3-yl）-1, 3-diarylpropan-l-ones is presented. The procedure utilizes phosphotungstic acid （5 mol%） as a catalyst for the Michael addition ...A new facile, efficient and very mild entry to the synthesis of 3-（1H-indol-3-yl）-1, 3-diarylpropan-l-ones is presented. The procedure utilizes phosphotungstic acid （5 mol%） as a catalyst for the Michael addition of indole to α,β-unsaturated ketones in good yield in acetonitrile as solvent.展开更多
An efficient method for the conjugate addition of indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) is reported. Products are isolated by a simple procedure that avoids an aqueous work up and extens...An efficient method for the conjugate addition of indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) is reported. Products are isolated by a simple procedure that avoids an aqueous work up and extensive chromatography, thus minimizing waste. Bismuth (III) compounds are especially attractive from a green chemistry perspective because they are remarkably nontoxic, non-corrosive and relatively inexpensive.展开更多
An efficient chiral Br?nsted acid-catalyzed conjugate addition of indoles to azadienes has been successfully developed,which enables a facile approach to optically active hetero-triarylmethanes with excellent enantios...An efficient chiral Br?nsted acid-catalyzed conjugate addition of indoles to azadienes has been successfully developed,which enables a facile approach to optically active hetero-triarylmethanes with excellent enantioselectivities and broad substrate scope.This chiral Br?nsted acid catalytic system provides a new opportunity for the development of asymmetric reactions of azadienes.展开更多
An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long M...An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long Min Wu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
A novel series of 5H-pyridazino[4,5-b]indoles were designed and synthesized in order to find novel potent anticancer compounds. The structures were confirmed by ^1H NMR and MS. Their antiproliferative activities again...A novel series of 5H-pyridazino[4,5-b]indoles were designed and synthesized in order to find novel potent anticancer compounds. The structures were confirmed by ^1H NMR and MS. Their antiproliferative activities against two cancer cell lines were tested by the MTT method in vitro. Three of compounds （1e, 1g, and 1h） exhibited potent antiproliferative activities, especially compound lh （with IC50 values of 5.2 μmol/L and 1.9 μmol/L against Bel-7402 and HT-1080, respectively）. The preliminary structure-activity relationships of 5H-pyridazino[4,5-b]indole derivatives were discussed.展开更多
An efficient asymmetric Friedel-Crafts reaction has been developed for the synthesis of optically active quaternaryα‐aminophosphonates with up to98%ee.The synthesis involves the reaction of cyclicα‐ketiminophospho...An efficient asymmetric Friedel-Crafts reaction has been developed for the synthesis of optically active quaternaryα‐aminophosphonates with up to98%ee.The synthesis involves the reaction of cyclicα‐ketiminophosphonates with indoles using an H8‐BINOL‐derived chiral phosphoric acid(CPA)catalyst that bears electron‐withdrawing3,5‐ditrifluoromethylphenyl substituents on its3‐and3′‐positions.This Friedel-Crafts reaction of cyclicα‐ketiminophosphonates was also successful with pyrrole.展开更多
C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols ge...C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols generally require a multi‐step procedure and stoichiometric promoters.Hereinwe develop a one‐step C2 prenylation of NH indole with cheap tert‐prenyl alcohol enabled by acidcatalysis.Salient features include good regioselectivity,step‐and atom‐economy,broad substratescope,and simple catalytic system.The mechanistic investigations demonstrate that both C2prenylation and C3 prenylation/migration pathways are engaged in the reaction.Notably,this practicalstrategy can be applied to the late‐stage diversification of tryptophan‐based peptides and concisesynthesis of tryprostatin B.展开更多
A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones...A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones.Mild reaction conditions,high diastereoselectivity,a broad substrate scope,effective functional group tolerance,and reasonable to remarkable yields were observed.展开更多
Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotrypto- phan emits in the visible region and is the smallest blue fluorescent amino acid probe for bio- logical applications. Other...Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotrypto- phan emits in the visible region and is the smallest blue fluorescent amino acid probe for bio- logical applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole- 4-carboxylate emits at 450 nrn with a long fluorescence lifetirne, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing esterderivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.展开更多
A soluble polymer-supported synthesis of indoles via palladium-mediated hetero- annulation of terminal alkynes with o-iodoanilines has been described. The protocol provides a useful tool for constructing combinatoria...A soluble polymer-supported synthesis of indoles via palladium-mediated hetero- annulation of terminal alkynes with o-iodoanilines has been described. The protocol provides a useful tool for constructing combinatorial indole libraries.展开更多
Based on the precedent discovery of a weak antifungal indole isolated from Aporpium caryae, which increased its activity when changing the N-alkyl chain, nineteen N-alkyl indoles, with alkyl chains from one to ten car...Based on the precedent discovery of a weak antifungal indole isolated from Aporpium caryae, which increased its activity when changing the N-alkyl chain, nineteen N-alkyl indoles, with alkyl chains from one to ten carbons and one or two hydroxyls, one amine or bromine functional groups, were prepared and fully characterized by spectroscopic methods. The aim of this study is the search for new synthetic agrochemical leads derived from natural products. The antifungal activity of the synthesized compounds against three fungal strains was measured in vitro. Six compounds presented good activity against Fusarium virguliforme, the causal agent of sudden-death syndrome (SDS) in soybean, in a bioautography assay. Four of them were tested in a germination test and in a greenhouse experiment. All tested compounds, applied as seed treatment, showed antifungal properties being effective to control SDS when there was low level of fungal contamination. Results indicate that some of the tested compounds are acting as growth inhibitors and represent new leads for the treatment of SDS for which no specific treatment has been previously reported.展开更多
Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cerea...Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cereals plants with allelopathic properties. Phytotoxic selectivity was evaluated from antialgal activity against the microalga Chlorella vulgaris, seed germination seeds and biomass weight of seedling of barley, rye, wheat, oat and maize species and the weed Lolium rigidum. Lipophilia character of the compounds was determined by RP-HPLC method. Both, the electronic character of the substituents, evaluated from σp parameter, and the lipophilia character of the molecules measured from logPHPLC parameter, are involved in the phytotoxic activity. The three bio indicators has shown that the compounds with the higher electron-acceptor groups showed the higher level of phytotoxicity and the molecules with electron-donor groups showed the lowest activity, although, in some cases, this behavior is modified by the lipophilic properties of the molecules. These results are rationalized in terms of polarization of N-H bond of heterocyclic ring. Compounds with the higher logPHPLC values showed the higher phytotoxic activity. Further evidence on the role of lipophilicity was obtained from linear regression between the average inhibitions percentages of biomass and logPHPLC values. The activity increased linearly by increasing the lipophilic character of the compounds. Therefore, quantitative effects in the phytotoxic activity of the electronic properties of the substituents in the aromatic ring and lipophilic character of the indoles can be inferred from σp and logPHPLC parameters, respectively. The results strongly suggest that the potential decomposition products of the natural indole alkaloids from cereals or other natural sources may be in connection with the allelopathic phenomenon of plants when are released into the soil.展开更多
A simple and efficient method for the synthesis of 3-indolyl-3-hydroxy oxindoles and unsymmetrical 3,3-di(indolyl)indolin-2-ones using microwave irradiation without catalyst and solvent is described. A series of 3-ind...A simple and efficient method for the synthesis of 3-indolyl-3-hydroxy oxindoles and unsymmetrical 3,3-di(indolyl)indolin-2-ones using microwave irradiation without catalyst and solvent is described. A series of 3-indolyl-3-hydroxy oxindoles and unsymmetrical 3,3-di(indolyl)indolin-2-ones have been synthesized in very short reaction times of 5 and 10 minutes and in yields ranging from 31% to 98% and from 53% to 78% respectively. This method offers a significant advantage over the conventional methods in terms of simplicity and shorter reaction time. To the best of our knowledge compounds N-allyl-3-hydroxy-3-(1-methyl-indol-3-yl)indolin-2-one (6c), N-allyl-3-hydroxy-3-(5-methoxy-indol-3-yl)indolin-2-one (8c), N-benzyl-3-hydroxy-3-(1-methyl-indol-3-yl) indolin-2-one (10c), N-propargyl-3-hydroxy-3-(1-methyl-indol-3-yl)indolin-2-one (13c), N-propargyl-3-hydroxy-3-(5-methoxy-indol-3-yl)indolin-2-one (14c), 3-(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (1e), 3-1-methyl(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (2e), 3-1-allyl(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (3e), 3-1-benzyl(5-methoxy-1H-in- dol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (4e) and 3-1-(prop-2-ynyl)(5-methoxy-1H-indol-3-yl)-3(1H-indol-3-yl)indolin-2-one (5e) are reported here for the first time. All the compounds are characterized by IR, 1H, 13C NMR and HRMS.展开更多
An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O a...An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O as the catalyst, various substituted indoles can react smoothly at room temperature to give the corresponding phthalides products in good to excellent yields (up to 96%).展开更多
Indole and its derivatives represent the most important heterocycles that are widely present in bioactive molecules,natural products and advanced materials,and thus functionalization of simple indoles to construct com...Indole and its derivatives represent the most important heterocycles that are widely present in bioactive molecules,natural products and advanced materials,and thus functionalization of simple indoles to construct complex indole derivatives is a research area of great current interest.2,3-Difunctionalization of indoles has been extensively studied,but the reported examples are limited to the synthesis of 2,3-disubstituted indole derivatives or dearomatized products containing central chirality.Until now,atroposelective 2,3-difunctionalization of simple indoles for the synthesis of axially chiral molecules is unknown.In this article,we report a straightforward and general strategy for atroposelective 2,3-difunctionalization of simple indoles,forming indole-containing axially chiral products in good yields and excellent enantioselectivities.The strategy we introduce herein may lead to the discovery of new approaches for multifunctionalization of indoles and other heterocyclic scaffolds,thus accessing novel axially chiral heteroarene-containing scaffolds that may find applications in medicinal chemistry and asymmetric catalysis.展开更多
Due to the high electrophilic nature of azo-dienophiles, azo-Diels–Alder proceeds rapidly even without the need of a catalyst and is therefore regarded as the “click reaction”. This spontaneity causes strong backgr...Due to the high electrophilic nature of azo-dienophiles, azo-Diels–Alder proceeds rapidly even without the need of a catalyst and is therefore regarded as the “click reaction”. This spontaneity causes strong background reaction and poses a daunting challenge to chemists for developing the catalytic asymmetric version. Reported herein is the first catalytic asymmetric dearomative azo-Diels–Alder reaction between2-vinylindoles and triazoledione. This protocol makes use of the high energy barrier of dearomatization to avert the strong background reaction of azo-Diels–Alder reaction, allowing the implementation of the projected reaction at ambient temperature. Density functional theory calculations have been performed to gain insights into the reaction mechanism and the origins of the enantioselectivity. By using this method,a variety of tetracyclic indole derivatives have been readily prepared in good to excellent yields and with excellent diastereo-and enantio–selectivities(33 examples, up to 97% yield and >99% ee, >20:1 dr).展开更多
Indole is a promising heteroarene in many natural products and pharmaceuticals;therefore, various synthetic methods for indole functionalizations have arisen in recent years. Herein, we report a Pd-catalyzed deoxygena...Indole is a promising heteroarene in many natural products and pharmaceuticals;therefore, various synthetic methods for indole functionalizations have arisen in recent years. Herein, we report a Pd-catalyzed deoxygenative coupling for the N-vinylation of indoles by employing vinyl ethers. The vinylated indoles could be readily prepared in good to excellent yields with N1-regioselectivity regardless of the electronic characteristics and substitution patterns of indole substrates. Some indole-based pharmaceutical molecules, such as gramine, evodiamine, rutaecarpine, and melatonine, are also successfully vinylated. Moreover, carbazoles and indazoles are shown to participate. Additionally, vinylated indole can readily transform into structurally interesting indole derivatives.展开更多
文摘This work presents a new greener alternative for biocondensation of aldehydes and indoles for the synthesis of bis- and tris(indolyl)methanes catalyzed by lemon juice (Citrus limon) in good yields under ultrasound irradiation in aqueous ethanol. Various substituted aldehydes with indoles under this reaction condition are elucidated. Also, tetraindolyl compounds were prepared using terephthaldialdehyde by following the same protocol. This method is an environmentally benign, efficient reaction, which requires shorter reaction time and simple experimental and work-up procedures.
基金UOV was supported in part by Conacyt through a doctoral fellowship. JLG thanks Conacyt for grant 237045, and AV thanks Conacyt for grant Fronteras 867.
文摘A global and local charge transfer partitioning model,based on the cornerstone theory developed by Robert G.Parr and Robert G.Pearson,which introduces two charge transfer channels(one for accepting electrons(electrophilic) and another for donating(nucleophilic)),is applied to the reaction of a set of indoles with 4,6-dinitrobenzofuroxan.The global analysis indicates that the prevalent electron transfer mechanism in the reaction is a nucleophilic one on the indoles,i.e.,the indoles under consideration transfer electrons to 4,6-dinitrobenzofuroxan.Evaluating the reactivity descriptorswith exchange-correlation functionals including exact exchange(global hybrids) yields slightly better correlations than those obtained with generalized gradient-approximated functionals;however,the trends are preserved.Comparing the trend obtained with the number of electrons donated by the indoles,and predicted by the partitioning model,with that observed experimentally based on the measured rate constants,we propose that the number of electrons transferred through this channel can be used as a nucleophilicity scale to order the reactivity of indoles towards 4,6-dinitrobenzofuroxan.This approach to obtain reactivity scales has the advantage of depending on the intrinsic properties of the two reacting species;therefore,it opens the possibility that the same group of molecules may show different reactivity trends depending on the species with which they are reacting.The local model allows systematic incorporation of the reactive atoms based on the their decreasing condensed Fukui functions,and the correlations obtained by increasing the number of reactive atoms participating in the local analysis of the transferred nucleophilic charge improve,reaching an optimal correlation,which in the present case indicates keeping three atoms from the indoles and two from 4,6-dinitrobenzofuroxan.The atoms selected by this procedure provide valuable information about the local reactivity of the indoles.We further show that this information about the most reactive atoms on each reactant,combined with the spatial distribution of the nucleophilic and electrophilic Fukui functions of both reactants,allows one to propose non-trivial candidates of starting geometries for the search of the transition state structures present in these reactions.
文摘A variety of indole derivatives were designed, synthesized and preliminarily evaluated for their in vitro cytotoxic activity in the A431 and H460 cell lines. All the compounds examined conferred unusual potency in a tumor cell cytotoxicity assay. The findings showed the indole derivatives would be a promising candidate for the development of new anticancer agents.
文摘A new facile, efficient and very mild entry to the synthesis of 3-（1H-indol-3-yl）-1, 3-diarylpropan-l-ones is presented. The procedure utilizes phosphotungstic acid （5 mol%） as a catalyst for the Michael addition of indole to α,β-unsaturated ketones in good yield in acetonitrile as solvent.
文摘An efficient method for the conjugate addition of indoles to a variety of chalcones using BiBr3 in ethanol (190 proof) is reported. Products are isolated by a simple procedure that avoids an aqueous work up and extensive chromatography, thus minimizing waste. Bismuth (III) compounds are especially attractive from a green chemistry perspective because they are remarkably nontoxic, non-corrosive and relatively inexpensive.
文摘An efficient chiral Br?nsted acid-catalyzed conjugate addition of indoles to azadienes has been successfully developed,which enables a facile approach to optically active hetero-triarylmethanes with excellent enantioselectivities and broad substrate scope.This chiral Br?nsted acid catalytic system provides a new opportunity for the development of asymmetric reactions of azadienes.
基金Project No. 20572040 was supported by National Natural Science Foundation of China.
文摘An efficient Michael addition of indoles to unsaturated enones, such as chalcones and β-nitrostyrenes, was achieved in the presence of a catalytic amount of nitrosonium tetrafluoroborate in ethyl ether. 2007 Long Min Wu. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘A novel series of 5H-pyridazino[4,5-b]indoles were designed and synthesized in order to find novel potent anticancer compounds. The structures were confirmed by ^1H NMR and MS. Their antiproliferative activities against two cancer cell lines were tested by the MTT method in vitro. Three of compounds （1e, 1g, and 1h） exhibited potent antiproliferative activities, especially compound lh （with IC50 values of 5.2 μmol/L and 1.9 μmol/L against Bel-7402 and HT-1080, respectively）. The preliminary structure-activity relationships of 5H-pyridazino[4,5-b]indole derivatives were discussed.
基金supported by the National Natural Science Foundation of China(21532006,21690074)~~
文摘An efficient asymmetric Friedel-Crafts reaction has been developed for the synthesis of optically active quaternaryα‐aminophosphonates with up to98%ee.The synthesis involves the reaction of cyclicα‐ketiminophosphonates with indoles using an H8‐BINOL‐derived chiral phosphoric acid(CPA)catalyst that bears electron‐withdrawing3,5‐ditrifluoromethylphenyl substituents on its3‐and3′‐positions.This Friedel-Crafts reaction of cyclicα‐ketiminophosphonates was also successful with pyrrole.
文摘C2 prenylated indoles are widespread in a variety of bioactive natural alkaloids.Therefore,theselective installation of prenyl group at C2 position of NH indoles is of great significance.However,the known protocols generally require a multi‐step procedure and stoichiometric promoters.Hereinwe develop a one‐step C2 prenylation of NH indole with cheap tert‐prenyl alcohol enabled by acidcatalysis.Salient features include good regioselectivity,step‐and atom‐economy,broad substratescope,and simple catalytic system.The mechanistic investigations demonstrate that both C2prenylation and C3 prenylation/migration pathways are engaged in the reaction.Notably,this practicalstrategy can be applied to the late‐stage diversification of tryptophan‐based peptides and concisesynthesis of tryprostatin B.
文摘A straightforward and efficient protocol for dearomatizing indoles is described.The reaction,catalyzed by an inexpensive Co(III)/Zn(II)catalyst,starts from easily accessible N‐pyrimidinyl indoles and ene‐yne ketones.Mild reaction conditions,high diastereoselectivity,a broad substrate scope,effective functional group tolerance,and reasonable to remarkable yields were observed.
基金supported by Beijing Natural Science Foundation(L172028)the National Natural Science Foundation of China(No.21773012 and No.91753118)+1 种基金the Recruitment Program of Global Youth Expertsthe Fundamental Research Funds for Central Universities
文摘Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotrypto- phan emits in the visible region and is the smallest blue fluorescent amino acid probe for bio- logical applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole- 4-carboxylate emits at 450 nrn with a long fluorescence lifetirne, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing esterderivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.
基金the National Natural Science Foundation of China (No. 29972037) and Foundation for University Key Teacher by the Ministry of Education.
文摘A soluble polymer-supported synthesis of indoles via palladium-mediated hetero- annulation of terminal alkynes with o-iodoanilines has been described. The protocol provides a useful tool for constructing combinatorial indole libraries.
文摘Based on the precedent discovery of a weak antifungal indole isolated from Aporpium caryae, which increased its activity when changing the N-alkyl chain, nineteen N-alkyl indoles, with alkyl chains from one to ten carbons and one or two hydroxyls, one amine or bromine functional groups, were prepared and fully characterized by spectroscopic methods. The aim of this study is the search for new synthetic agrochemical leads derived from natural products. The antifungal activity of the synthesized compounds against three fungal strains was measured in vitro. Six compounds presented good activity against Fusarium virguliforme, the causal agent of sudden-death syndrome (SDS) in soybean, in a bioautography assay. Four of them were tested in a germination test and in a greenhouse experiment. All tested compounds, applied as seed treatment, showed antifungal properties being effective to control SDS when there was low level of fungal contamination. Results indicate that some of the tested compounds are acting as growth inhibitors and represent new leads for the treatment of SDS for which no specific treatment has been previously reported.
文摘Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cereals plants with allelopathic properties. Phytotoxic selectivity was evaluated from antialgal activity against the microalga Chlorella vulgaris, seed germination seeds and biomass weight of seedling of barley, rye, wheat, oat and maize species and the weed Lolium rigidum. Lipophilia character of the compounds was determined by RP-HPLC method. Both, the electronic character of the substituents, evaluated from σp parameter, and the lipophilia character of the molecules measured from logPHPLC parameter, are involved in the phytotoxic activity. The three bio indicators has shown that the compounds with the higher electron-acceptor groups showed the higher level of phytotoxicity and the molecules with electron-donor groups showed the lowest activity, although, in some cases, this behavior is modified by the lipophilic properties of the molecules. These results are rationalized in terms of polarization of N-H bond of heterocyclic ring. Compounds with the higher logPHPLC values showed the higher phytotoxic activity. Further evidence on the role of lipophilicity was obtained from linear regression between the average inhibitions percentages of biomass and logPHPLC values. The activity increased linearly by increasing the lipophilic character of the compounds. Therefore, quantitative effects in the phytotoxic activity of the electronic properties of the substituents in the aromatic ring and lipophilic character of the indoles can be inferred from σp and logPHPLC parameters, respectively. The results strongly suggest that the potential decomposition products of the natural indole alkaloids from cereals or other natural sources may be in connection with the allelopathic phenomenon of plants when are released into the soil.
文摘A simple and efficient method for the synthesis of 3-indolyl-3-hydroxy oxindoles and unsymmetrical 3,3-di(indolyl)indolin-2-ones using microwave irradiation without catalyst and solvent is described. A series of 3-indolyl-3-hydroxy oxindoles and unsymmetrical 3,3-di(indolyl)indolin-2-ones have been synthesized in very short reaction times of 5 and 10 minutes and in yields ranging from 31% to 98% and from 53% to 78% respectively. This method offers a significant advantage over the conventional methods in terms of simplicity and shorter reaction time. To the best of our knowledge compounds N-allyl-3-hydroxy-3-(1-methyl-indol-3-yl)indolin-2-one (6c), N-allyl-3-hydroxy-3-(5-methoxy-indol-3-yl)indolin-2-one (8c), N-benzyl-3-hydroxy-3-(1-methyl-indol-3-yl) indolin-2-one (10c), N-propargyl-3-hydroxy-3-(1-methyl-indol-3-yl)indolin-2-one (13c), N-propargyl-3-hydroxy-3-(5-methoxy-indol-3-yl)indolin-2-one (14c), 3-(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (1e), 3-1-methyl(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (2e), 3-1-allyl(5-methoxy-1H-indol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (3e), 3-1-benzyl(5-methoxy-1H-in- dol-3-yl)-3-(1H-indol-3-yl)indolin-2-one (4e) and 3-1-(prop-2-ynyl)(5-methoxy-1H-indol-3-yl)-3(1H-indol-3-yl)indolin-2-one (5e) are reported here for the first time. All the compounds are characterized by IR, 1H, 13C NMR and HRMS.
文摘An efficient and facile method for the synthesis of 3-indolyl-substituted phthalides by Friedel-Crafts alkylation of indoles with 3-hydroxyisobenzofuran-1(3H)-one has been developed. Using only 2 mol-% TsOH·H2O as the catalyst, various substituted indoles can react smoothly at room temperature to give the corresponding phthalides products in good to excellent yields (up to 96%).
文摘Indole and its derivatives represent the most important heterocycles that are widely present in bioactive molecules,natural products and advanced materials,and thus functionalization of simple indoles to construct complex indole derivatives is a research area of great current interest.2,3-Difunctionalization of indoles has been extensively studied,but the reported examples are limited to the synthesis of 2,3-disubstituted indole derivatives or dearomatized products containing central chirality.Until now,atroposelective 2,3-difunctionalization of simple indoles for the synthesis of axially chiral molecules is unknown.In this article,we report a straightforward and general strategy for atroposelective 2,3-difunctionalization of simple indoles,forming indole-containing axially chiral products in good yields and excellent enantioselectivities.The strategy we introduce herein may lead to the discovery of new approaches for multifunctionalization of indoles and other heterocyclic scaffolds,thus accessing novel axially chiral heteroarene-containing scaffolds that may find applications in medicinal chemistry and asymmetric catalysis.
基金the generous financial support from Natural Science Foundation of Henan Province (No.222300420084)application research plan of Key Scientific Research Projects in Colleges and Universities of Henan Province (No.22A150056)+1 种基金the Youth Innovation Team Program in Colleges and Universities of Shandong Province (No.2022KJ228)National Natural Science Foundation of China (No.22208302)。
文摘Due to the high electrophilic nature of azo-dienophiles, azo-Diels–Alder proceeds rapidly even without the need of a catalyst and is therefore regarded as the “click reaction”. This spontaneity causes strong background reaction and poses a daunting challenge to chemists for developing the catalytic asymmetric version. Reported herein is the first catalytic asymmetric dearomative azo-Diels–Alder reaction between2-vinylindoles and triazoledione. This protocol makes use of the high energy barrier of dearomatization to avert the strong background reaction of azo-Diels–Alder reaction, allowing the implementation of the projected reaction at ambient temperature. Density functional theory calculations have been performed to gain insights into the reaction mechanism and the origins of the enantioselectivity. By using this method,a variety of tetracyclic indole derivatives have been readily prepared in good to excellent yields and with excellent diastereo-and enantio–selectivities(33 examples, up to 97% yield and >99% ee, >20:1 dr).
基金supported by the National Key Research and Development Program of China (2022YFB4101800)the National Natural Science Foundation of China (22231002)the Guangdong Basic and Applied Basic Research Foundation (2024B1515040027)。
文摘Indole is a promising heteroarene in many natural products and pharmaceuticals;therefore, various synthetic methods for indole functionalizations have arisen in recent years. Herein, we report a Pd-catalyzed deoxygenative coupling for the N-vinylation of indoles by employing vinyl ethers. The vinylated indoles could be readily prepared in good to excellent yields with N1-regioselectivity regardless of the electronic characteristics and substitution patterns of indole substrates. Some indole-based pharmaceutical molecules, such as gramine, evodiamine, rutaecarpine, and melatonine, are also successfully vinylated. Moreover, carbazoles and indazoles are shown to participate. Additionally, vinylated indole can readily transform into structurally interesting indole derivatives.
