N-methyl Indole Research Articles

C-Dimethylated Flavones as Possible Potential Anti-Tubercular and Anticancer Agents.

The present investigation describes an intramolecular Oxa-Michael addition of penta-substituted phenols to the enone of the tether in the presence of iodine as the oxidizing agent. Ten C-Dimethylated flavones with moderate to good yields (10a-j, 60-89 %) were isolated by heating the corresponding C-dimethylated chalcones using iodine in DMSO. Using the Microplate Alamar Blue test (MABA) technique, the drugs' quantitative drug susceptibility against the H37Rv strain of replicating Mycobacterium TB was determined. The sensitivity of two of the developed compounds (10e, 10h) was up to 6.25 g/mL. The human lung adenocarcinoma cell lines (A549) were used in the anticancer study, which was carried out using the MTT cell proliferation assay. In A549 cell lines, four flavones demonstrated anticancer activity with IC50 values between 39 and 48 μM. The C-dimethylated flavones, 10b (3,4-dimethoxy), 10c (2,3,4-trimethoxy), 10e (p-fluoro) and 10g (N-methyl indole) substitutions on ring 'B' showed good anticancer activity with IC50 values 39.17, 39.21, 48.43 and 43.48 μM, respectively. The compounds 10b, 10c, 10d, 10e, and 10i had improved binding and interaction profiles among all the compounds examined during the current In Silico research, as shown by the docking simulations against two targets EGFR and MTB MurI.

Methyl 9-(1-methyl-1H-indol-3-yl)-9-oxononanoate

Methyl 9-(1-methyl-1H-indol-3-yl)-9-oxononanoate was synthesized using Friedel–Crafts acylation between N-methyl indole and methyl 9-chloro-9-oxononanoate. The structure of the newly synthesized compound was elucidated using 1H-NMR, 13C-NMR, NOESY-1D, ESI-MS, FT-IR, and UV-Vis spectroscopy.

3-Alkynylindoles as Building Blocks for the Synthesis of Electronically Tunable Indole-Based Push-Pull Chromophores.

In this study, two different classes of push–pull chromophores were synthesized in modest to excellent yields by formal [2+2] cycloaddition-retroelectrocyclization (CA-RE) reactions. N-Methyl indole was introduced as a new donor group to activate alkynes in the CA-RE transformations. Depending on the side groups’ size and donor/acceptor characteristics, N-methyl indole-containing compounds exhibited λmax values ranging between 378 and 658 nm. The optoelectronic properties of the reported D–A-type structures were studied by UV/vis spectroscopy and computational studies. The complete regioselectivity observed in the products was elaborated by one-dimensional (1D) and two-dimensional (2D) NMR studies, and the electron donor strength order of N-alkyl indole and triazene donor groups was also established. The intramolecular charge-transfer characteristics of the target push–pull chromophores were investigated by frontier orbital depictions, electrostatic potential maps, and time-dependent density functional theory calculations. Overall, the computational and experimental results match each other. Integrating a new donor group, N-alkyl indole, into the substrates used in formal [2+2] cycloaddition-retroelectrocyclizations has significant potential to overcome the limited donor-substituted substrate scope problem of CA-RE reactions.

Visible-light induced Cross-Dehydrogenative-Coupling (CDC) reactions of N-aryl tetrahydroisoquinolines under aerobic conditions

A visible-light induced cross-dehydrogenative-coupling (CDC) reaction of N-aryl tetrahydroisoquinolines was developed under mild aerobic conditions. This protocol proceeded smoothly with a large range of nucleophiles (nitroalkane, dimethyl phosphite, dimethyl malonate, N-methyl indole, TMSCN) under metal-free conditions and an oxygen atmosphere, forming a new CC bond. Visible-light played a significant acceleration effect in this reaction.

C-dimethylated Chalcones:Towards Possible Dual Acting Agents-Against Tuberculosis and cancer(A549) and an SAR study

A series of seventeen C-dimethyl chalcones on ring ‘A’ were synthesized by using a known condensation method. The chalcones include the utilization of heterocyclic aldehydes such as N,N-dimethyl benzaldehyde, furfural-2-aldehyde, and N-methyl indole aldehyde. All the compounds were found to possess moderate to potent anticancer activity on human lung adenocarcinoma cell line “A549” in the MTT cell proliferation method. The dimethyl chalcone 9f with furfural ring was found to possess potent anti-cancer activity followed by 9m with o-chloro substitution on ring ‘B’ with IC50values of 1.0 and 1.2 μg/mL respectively. Similarly compounds 9n, 9j, 9g, 9k, 9p, 9d, 9b,and 9ealso showed good anti-cancer activity (IC50values from 6.5 to 9.8μg/mL). Further, the compounds were also compared with the known anti-TB activities in order to ascertain their properties towards dual acting agents against tuberculosis and cancer for more beneficiaries.

Novel nicotinoyl pyrazoline derivates bearing N-methyl indole moiety as antitumor agents: Design, synthesis and evaluation

In the present work, twenty-five nicotinoyl pyrazoline derivates bearing N-methyl indole moiety have been designed and synthesized. The biological evaluation of these compounds as tubulin assembly inhibitors revealed that most of them were potential antitumor agents. Among them, compound 28 exhibited most potency against cancer cell line panels (GI50 = 29–90 nM for HeLa, HepG2 and MCF-7 cells) without toxicity to non-tumor cells (CC50 > 300 μM for 293 T cell), bound to the colchicine site of tubulin and displayed excellent inhibitory activity in tubulin assembly assay (IC50 = 1.6 μM, better than CA-4). Molecular dynamics simulation was carried out to validate the docking pose of compound 28 with tubulin crystalline. Further investigation on HepG2 and HeLa cells demonstrated that compound 28 could cause mitosis arrest to G2/M phase, and subsequently induced cell apoptosis. The efficiency in vivo of compound 28 was also evaluated on HeLa-Xenograft nude mice, and the relative tumor inhibition ration was up to 61.52% without noticeable weight loss and tissue damage (examined by H&E staining), which was comparable to CA-4 (inhibited 59.92%). In brief, compound 28 is a promising candidate for tumor therapy as tubulin assembly inhibitor.

ChemInform Abstract: Synthesis of 7‐Hydroxy‐6,7‐dihydro‐indole and 6′,7′‐Dihydro‐3,7′‐biindole Derivatives from Domino Reactions of Arylglyoxals or Methyl Ketones with Enamines.

A series of interesting 7-hydroxy-2-aryl-6,7-dihydro-indol-4(5H)-ones 3 was successfully synthesized in moderate to good yields by the domino reactions of different arylglyoxals 1 with enamines 2 under catalyst-free conditions. 7-Hydroxy-2-aryl-6,7-dihydro-indol-4(5H)-ones 3 could also be prepared in moderate yields by the iodine-promoted one pot-two step reactions of methyl ketones 6 with enamines 2. The reaction of 3a with N-methyl indole 7a in the presence of PTSA afforded 2′-aryl-6′,7′-dihydro-[3,7′-biindol]-4′(5′H)-ones 8a in 81% yield. In addition, 3,7′-bis-indoles 8 could also be observed in 47–73% yields by one pot domino reaction of arylglyoxals 1 with enamines 2 and indoles 7 over two steps. This protocol provides a simple and practical method to construct diverse 7-hydroxy-6,7-dihydro-indole derivatives 3 and 3,7′-bis-indoles 8 from easily obtained starting materials.

Copper‐Catalyzed CH Bond Direct Chalcogenation of Aromatic Compounds Leading to Diaryl Sulfides, Selenides, and Diselenides by Using Elemental Sulfur and Selenium as Chalcogen Sources Under Oxidative Conditions

The reactions of aromatic compounds and elemental chalcogens catalyzed by a copper salt with molecular oxygen as an oxidant were carried out. The reaction of 3-substituted imidazo[1,5-a]pyridines and elemental sulfur in the presence of CuTC (copper(I) thiophenecarboxylate) gave the corresponding bisimidazopyridyl sulfides in good to quantitative yields. The reaction proceeded even under aerobic oxidation conditions. The use of a polar solvent was crucial for the reaction, and DMSO (dimethyl sulfoxide) in particular stimulated the reaction. The reaction could be applied to common aromatic compounds, such as N-methyl indole and dialkyl anilines. The reaction of indole proceeded at the nucleophilic C3 position rather than at the acidic C2 position. In addition, the reaction of dialkyl anilines proceeded with an ortho, para orientation. The reactions of imidazopyridines and elemental selenium under similar conditions gave the corresponding bisimidazopyridyl diselenides along with bisimidazopyridyl monoselenides. The resulting diselenides were readily converted to the corresponding monoselenides with unreacted imidazopyridines under the same conditions. The reaction could be applied to the copolymerization of bifunctional bisimidazopyridines and elemental sulfur to give oligomeric copolymers in quantitative yield.

Polyvinylpolypyrrolidone-supported triflic acid (PVPP·OTf) as a new, efficient, and recyclable heterogeneous catalyst for the synthesis of bis-indolyl methane derivatives

Abstract A simple, inexpensive, environmentally friendly and efficient route for the synthesis of bis-indolyl methane derivatives by the reaction of indole or N-methyl indole with aldehydes using polyvinylpolypyrrolidone-supported triflic acid (PVPP·OTf) as a catalyst is described. PVPP·OTf catalyst is air-stable, heterogeneous, cost-effective, easy to handle, and easily removed from the reaction mixtures.

Choline Chloride/Urea Ionic Liquid Catalyzed a Convenient One-Pot Synthesis of Indole-3-propanamide Derivatives

A sequential three-component reaction of aromatic aldehydes with Meldrum's acid and N-methyl indole in the presence of choline chloride/urea ionic liquid as green catalyst has been described. In this one-pot multicomponent reaction, a series of indole-3-propanamide derivatives were synthesized with good to excellent yields. This methodology shows several advantages including fast reaction, easy isolation, operational simplicity that make it a useful and attractive option for the library generation of indole-3-propanamides (5a–l) for drug discovery. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

CuO/SiO2 as a simple, effective and recoverable catalyst for alkylation of indole derivatives with diazo compounds

The purely inorganic copper oxide on silica catalyzes the reaction of methyl phenyldiazoacetate with N-methyl indole under mild reaction conditions, giving the alkylation (formally a C-H insertion) in position 3, and the catalyst can be recovered and reused at least in 5 consecutive runs with only minor loss in activity. The scope of the reaction includes various diazo compounds and indole or pyrrole derivatives leading to alkylation or cyclopropanation depending on the heterocycle structure. An alternative mechanism, without reduction of Cu(II) to Cu(I), is proposed on the basis of the obtained results.

A Labeled Substrate Approach to Discovery of Biocatalytic Reactions: A Proof of Concept Transformation with N-Methylindole

Biocatalysis has become an important method in the pharmaceutical industry for the incorporation of new functionality in small molecules. Currently this method is limited in the types of reactions that can be carried out and no strategy exists to systematically screen for new biocatalyzed reactions. This study involves the development of a medium throughput screen to identify and optimize new reactions using a series of marine-derived bacterial cell lines, which were screened against several (13)C labeled organic substrates. The reactions were analyzed using (13)C NMR as the primary screening tool. We describe the discovery of a bacterial catalyzed indole oxidation reaction in which complete conversion of (13)C labeled N-methyl indole to 3-hydroxyindole was observed. In addition, the sensitivity of this reaction to dO(2) levels can be exploited to oxidize to either 3-hydroxyindole or 2-oxoindole. This new platform sets up an important tool for the discovery of new organic transformations using an extensive library of marine bacteria.

A simple, efficient and green procedure for the synthesis of bis-indolyl methanes in 1,1,1,3,3,3-hexafluoro-2-propanol

A simple, inexpensive, environmentally friendly and efficient route for the synthesis of bis-indolyl methanes derivatives by the reaction of indole or N-methyl indole with aldehydes using hexafluoroisopropanol as a solvent is described. The solvent (HFIP) can be readily separated from reaction products and recovered in excellent purity for direct reuse.

Pentafluorophenylammonium triflate as an efficient, environmentally friendly and novel organocatalyst for synthesis of bis-indolyl methane derivatives

A simple, inexpensive, environmentally friendly and efficient route for the synthesis of bis-indolyl methane derivatives by the reaction of indole or N-methyl indole with aldehydes using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. PFPAT organocatalyst is air-stable, cost-effective, easy to handle, and easily removed from the reaction mixtures.

Homogeneous dehydrogenation of liquid organic hydrogen carriers catalyzed by an iridium PCP complex

The activity of the PCP pincer complex IrH2{C6H3-2,6-(OPBu(t)2)2)}, (3) as a catalyst for the dehydrogenation of the potential liquid organic hydrogen carriers: perhydro-dibenzofuran (4), perhydro-indole (5), N-methyl perhydro-indole (6), 4,4'-bipiperridine (7), 4-amino-methylpiperridine (8), and aminomethylcyclohexane (9) was investigated. Only low levels of dehydrogenation were achieved with 4 at 150 and 200 degrees C except in the presence a hydrogen acceptor, 3,3-dimethyl-1-butene (tbe). At temperatures above 150 degrees C, 3 showed high activity with 5 but only for the release of H2 across the C-N bond. Dehydrogenation of 6 at 150 degrees C was found to release up to 2.9 wt% H2, giving N-methyl tetrahydroindole in 92% yield, but only 7% N-methyl indole. However, efficient dehydrogenation of the aliphatic hydrogens occurred at 200 degrees C giving mixtures that approached a approximately 1:3 equilibrium between N-methyl indole and N-methyl tetrahydroindole at longer reaction times. The pincer catalyst was observed to be effective for the dehydrogenation of 7 and 8 at 200 degrees C but the products polymerize. The catalytic dehydrogenation of 9 was very efficient at 200 degrees C but gave primarily the undesired products dibenzylamine (68%), benzylidenebenzylamine (22%), ammonia and only minor amount of benzonitrile (10%). At 160 degrees C, 85% of the substrate was consumed after 24 h of heating but only a minor amount of cyclohexanecarbonitrile (2%) was detected with the major products being biscyclohexylmethylamine (45%) and cyclohexylmethyl-cyclohexylimine (38%). The nitrile yield is remarkably improved to 97% when the dehydrogenation was carried out at 160 degrees C in the presence of 10 mol% NaOBu(t) but heating the reaction mixtures containing the base to 200 degrees C resulted in the decomposition of the pincer catalyst.

Platinum‐Catalyzed Multi‐Step Reaction of Propargyl Alcohols with N‐Heteroaromatics

N-Methyl indole reacts with but-2-yn-1-ol in the presence of PtCl(2) in MeOH giving indole derivatives having a substituted 3-oxobutyl group at the 3-position in good yield. Under the reaction conditions, various substituted indoles and substituted propargyl alcohols are successfully involved in the reaction giving the corresponding addition products in good to moderate yields. The catalytic reaction can be further extended to N-phenyl pyrrole. In the present multi-step reaction, PtCl(2) likely plays dual roles: as the catalyst for the rearrangement of propargyl alcohols to the corresponding alkenyl ketones and as the catalyst for the addition of indoles to the alkenyl ketones. Experimental evidence is provided to support the proposed mechanism.

Platinum‐Catalyzed Multistep Reactions of Indoles with Alkynyl Alcohols

PtCl2 effectively catalyzes the multistep reaction of N-methyl indole (1 a) with pent-3-yn-1-ol (2 a) in THF at room temperature for 2 h to give indole derivative 3 a, which contains a five-membered cyclic ether group at C3 in 93% yield. Under similar reaction conditions, various substituted N-methyl indoles 1 b-h and indole (1 i) reacted efficiently with 2 a to afford the corresponding indole derivatives 3 b-h and 3 i in 48-91 and 72% yields. The results showed that N-methyl indoles with electron-donating substituents were more reactive affording higher product yields than those with electron-withdrawing groups. Likewise, various substituted but-3-yn-1-ols 2 b-e and other longer chain alkynyl alcohols 2 f-i also underwent a cyclization-addition reaction with N-methyl indole (1 a) to provide the corresponding cyclization-addition products 3 j-m and 3 a, 3 j, and 3 n-o in good to excellent yields. The present platinum-catalyzed cyclization-addition reaction can be further extended into N-methyl pyrrole. Mechanistically, the catalytic reaction proceeds by an intramolecular hydroalkoxylation of alkynyl alcohol to afford cyclic enol ether followed by the addition of the C--H bond of indole to the unsaturated moiety of cyclic enol ether providing the final product. Experimental evidence to support this proposed mechanism is provided.

New Heck coupling strategies for the synthesis of paullone and dimethyl paullone

The short total synthesis of paullone ( 1) and dimethyl paullone ( 2) via a novel palladium-catalyzed intramolecular coupling using the o-bromo- and o-iodo anilides of indoles ( 3 and 3a) and N-methyl indole 4 is described.

Pyrrolizidine Esters and Amides as 5-HT4 Receptor Agonists and Antagonists

A series of pyrrolizidine esters, amides, and ureas was prepared and tested for 5-HT(4) and 5-HT(3) receptor binding, 5-HT(4) receptor agonism in the rat tunica muscularis mucosae (TMM) assay, and for 5-HT(3) receptor-mediated functional antagonism in the Bezold-Jarisch reflex assay. Several pyrrolizidine derivatives were identified with high affinity for the 5-HT(4) receptor, including benzamide 12a (SC-53116), a potent and selective 5-HT(4) partial agonist that exhibits efficacy in promoting antral contractions and activity in promoting gastric emptying in canine models. Also discovered were 5-HT(4) receptor antagonists, including imidazopyridine amide 12h (SC-53606), which is a potent and selective 5-HT(4) receptor antagonist with a pA(2) value of 8.13 in the rat TMM assay. N-Methyl indole ester 13d was identified as a potent 5-HT(4) antagonist with a pA(2) value of 8.93. High selectivity was observed for these pyrrolizidine derivatives versus other monoamine receptors, including 5-HT(1), 5-HT(2), D(1), D(2), alpha(1), alpha(2), and beta receptors.

Towards phase-transfer catalysts with a chiral anion: inducing asymmetry in the reactions of cations

The ability of chiral anions, for example bis[1,1′-bi-2-naphtholato]borate, to induce asymmetry in the reactions of prochiral cations was investigated. Ion-pairing of a borate anion with an aziridinium ion was demonstrated by NMR spectroscopy. The addition of N-methyl indole to an iminium ion (benzylidenedimethylammonium) and the ring-opening of an aziridinium ion (1,2-diphenyl-3-azonia-spiro[2.4]heptane) with benzylamine were studied. Low, but significant, (<15%) enantioselectivities were induced in the formation of the diamine benzyl-(1′,2′-diphenyl-2-pyrrolidin-1-yl-ethyl)-amine. The counterion of the additive was found to have a remarkable effect on the yield and the sense of enantioselectivity of these reactions.