Iodine-Catalyzed Annulation Reaction of Ortho-Formylarylketones with Indoles: A General Strategy for the Synthesis of Indolylbenzo[b]carbazoles.

The iodine-catalyzed cascade reaction of ortho-formylarylketones with indoles for the synthesis of indolylbenzo[b]carbazoles is reported. The reaction is initiated in the presence of iodine by two successive nucleophilic additions of indoles with an aldehyde group of ortho-formylarylketones, and the ketone does not undergo a nucleophilic addition and only involves in the Friedel-Crafts-type cyclization. A variety of substrates are tested, and the efficiency of this reaction is demonstrated with gram-scale reactions.

One-Pot Knoevenagel/Imination/6π-Azaelectrocyclization Sequence for the Synthesis of Disubstituted Nicotinonitriles.

We report on a copper-catalyzed three-component reaction for the synthesis of disubstituted nicotinonitriles using 3-bromopropenals, benzoylacetonitriles, and ammonium acetate (NH4OAc). The Knoevenagel-type condensation of 3-bromopropenals with benzoylacetonitriles gives δ-bromo-2,4-dienones that contain strategically placed functional groups that react with the ammonia generated in situ to give the corresponding azatrienes. These azatrienes can then be transformed into trisubstituted pyridines under the reaction conditions via a reaction sequence involving 6π-azaelectrocyclization and aromatization.

Iodine-Catalyzed Regioselective Synthesis of Diphenyl-Substituted Carbazoles via [4 + 2] Annulation of ß-Formyl Ketones with Indoles.

The [4 + 2] annulation of ß-formyl ketones with an indole has been developed for the regioselective synthesis of diphenyl-substituted carbazoles in the presence of a catalytic amount of iodine. The 1,4-dicarbonyl compound containing a phenyl group at the α-position of an aldehyde group reacts more readily with indoles to form carbazole derivatives. Using this method, a variety of carbazole derivatives can be readily accessed under mild reaction conditions.

Investigating Therapeutic Effects of Indole Derivatives Targeting Inflammation and Oxidative Stress in Neurotoxin-Induced Cell and Mouse Models of Parkinson's Disease.

Neuroinflammation and oxidative stress have been emerging as important pathways contributing to Parkinson's disease (PD) pathogenesis. In PD brains, the activated microglia release inflammatory factors such as interleukin (IL)-ß, IL-6, tumor necrosis factor (TNF)-α, and nitric oxide (NO), which increase oxidative stress and mediate neurodegeneration. Using 1-methyl-4-phenylpyridinium (MPP+)-activated human microglial HMC3 cells and the sub-chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD, we found the potential of indole derivative NC009-1 against neuroinflammation, oxidative stress, and neurodegeneration for PD. In vitro, NC009-1 alleviated MPP+-induced cytotoxicity, reduced NO, IL-1ß, IL-6, and TNF-α production, and suppressed NLR family pyrin domain containing 3 (NLRP3) inflammasome activation in MPP+-activated HMC3 cells. In vivo, NC009-1 ameliorated motor deficits and non-motor depression, increased dopamine and dopamine transporter levels in the striatum, and reduced oxidative stress as well as microglia and astrocyte reactivity in the ventral midbrain of MPTP-treated mice. These protective effects were achieved by down-regulating NLRP3, CASP1, iNOS, IL-1ß, IL-6, and TNF-α, and up-regulating SOD2, NRF2, and NQO1. These results strengthen the involvement of neuroinflammation and oxidative stress in PD pathogenic mechanism, and indicate NC009-1 as a potential drug candidate for PD treatment.

Synthesis of Unsymmetrical Urea Derivatives via Cu-Catalyzed Reaction of Acylazide and Secondary Amine.

The synthesis of unsymmetrical urea generally requires toxic reagent, solvent and harsh reaction condition. Herein, we introduce Cu-catalyzed greener and safer unsymmetrical urea derivatives synthesis in ethyl acetate. This method minimized utilization of toxic reagent. A variety of indole, amines, and azides with bis-indole successfully employed leading to high yields and gram scale synthesis of isolated urea.

Copper-catalysed synthesis of 3-hydroxyisoindolin-1-ones from benzylcyanide 2-iodobenzamides.

An efficient one-pot two-step sequential reaction for the synthesis of biologically active 3-hydroxyisoindolin-1-one derivatives from 2-iodobenzamide derivatives and various substituted benzyl cyanides in the presence of CuCl and cesium carbonate in DMSO is reported. Furthermore, 3-hydroxyisoindolinone derivatives possessing bromo substituents were obtained from 2-iodobenzamide and 2-bromobenzyl cyanide substrates in two steps. Benzyl cyanide has been successfully used for the first time as a benzoyl synthon for the synthesis of 3-hydroxyisoindolin-1-ones. Interestingly, the mechanism of formation of 3-hydroxyisoindolin-1-ones is a novel pathway that involves carbon degradation followed by ring contraction.

Synthesis of Polysubstituted Cyclopentene and Cyclopenta[ b]carbazole Analogues from Unsymmetrical 4-Arylidene-3,6-diarylhex-2-en-5-ynal and Indole Derivatives via an Iodine Mediated Electrocyclization Reaction.

An efficient method for the synthesis of polysubstituted cyclopentene and cyclopenta[ b]carbazole derivatives through the iodine-promoted electrocyclization of substituted indoles and 4-arylidene-3,6-diarylhex-2-en-5-ynal derivatives is reported. Polysubstituted cyclopentene derivatives were produced through 4π electrocyclization reactions with indole, 7-methylindole, and 5-bromoindole as coupling partners, whereas cyclopenta[ b]carbazole derivatives were produced via 6π electrocyclization in the case of methoxy (-OMe)-substituted indoles. The methods reported herein diastereo- and regioselectively proceed under straightforward and mild conditions.

A triazole-conjugated benzoxazone induces reactive oxygen species and promotes autophagic apoptosis in human lung cancer cells.

Numerous approaches suggested that compounds with conjugated triazole moieties or benzoxazone pharmacores are effective to antagonize proliferation of human tumors. The current study reported that a synthetic triazole-conjugated benzoxazone, 4-((5-benzyl-1H-1,2,3-triazol-3-yl)-methyl)-7-methoxy-2H-benzo[b][1,4]-oxazin-3(4H)-one (BTO), inhibited growth rates of human non-small cell lung cancer cells. The cytotoxicity can be enhanced with increasing drug concentrations. More evidence supported that the induced reactive oxygen species lead to ultimate apoptotic cell death by recruiting autophagy. The mechanistic pathway as elucidated involved tumor suppressor p53 activation and LC3-1 conversion followed by PARP and procaspase-3 cleavage. Autophagy inhibition reverted apoptotic death and restored cell viabilities. BTO suppressed the development of A549 cell xenograft tumors by activating autophagy and apoptosis simultaneously. As an efficient tumor growth inhibitor with relatively small molecular weight, BTO is a viable addition to the existing list of lung cancer treatment.

Copper-Catalyzed Cascade Synthesis of 2-Aryl-3-cyanobenzofuran and Dibenzo[ b, f]oxepine-10-carbonitrile Derivatives.

The copper-catalyzed reaction of aryl aldehydes with 2-iodobenzylcyanides afforded 2-aryl-3-cyanobenzofurans in isolated yields of up to 74% in a cascade manner, which involves Knoevenagel condensation, aryl hydroxylation, oxa-Michael addition, and aromatization reactions. Conversely, 2-halo benzaldehydes as reacting partners with 2-iodobenzylcyanide regioselectively furnished dibenzo[ b,f]oxepine-10-carbonitrile derivatives up to 85% isolated yields via tandem Knoevenagel condensation, aryl hydroxylation, and Ullmann coupling reactions.

A potent indolylquinoline alleviates growth of human lung cancer cell tumorspheres.

To fight cancer at its roots by targeting cancer stem cells is a promising approach for therapy. Previously, an indolylquinoline derivative, 3-((7-ethyl-1H-indol-3-yl)-methyl)-2-methylquinoline (EMMQ), was reported effectively inhibiting the growth of lung cancer cells through impairment of cellular mitochondria functions. To address more on drug efficiency, the study further exploited if EMMQ can impede the propagation of tumorspheres stemmed from non-small cell lung cancer cells. EMMQ inhibited proliferation of spheroids in culture. In animal models, administration of the drug attenuated the spheroid tumorigenicity. The activated apoptosis alleviated growth of xenograft tumors in immune-deficient mice as established by the enriched tumorspheres. More evidence suggested that the reduced stemness of the spheroid tumors is attributed to apoptotic death. The findings supported that EMMQ is an eligible approach to eradicate the minor but tumorigenic lung cancer tumorspheres.

Synthesis of Biologically Active Indenoisoquinoline Derivatives via a One-Pot Copper(II)-Catalyzed Tandem Reaction.

A concise route for the synthesis of indenoisoquinoline derivatives from 2-iodobenzamide and 1,3-indanedione derivatives in the presence of copper(II) chloride and cesium carbonate in acetonitrile solvent is reported. A wide variety of 2-iodobenzamide derivatives and indandiones could be used to synthesize indenoisoquinoline derivatives and other fused indenoisoquinoline in moderate to good yields. This methodology was adapted for the one-step synthesis of a series of clinically active topoisomerase I inhibitors such as NSC 314622, LMP-400, LMP-776.

Synthesis of Benzopyridoindolone Derivatives via a One-Pot Copper Catalyzed Tandem Reaction of 2-Iodobenzamide Derivatives and 2-Iodobenzylcyanides.

An efficient approach for the synthesis of benzo-fused pyridoindolone derivatives via a one-pot copper catalyzed tandem reaction of 2-iodobenzamides with 2-iodobenzylcyanides has been developed. Using this protocol, benzo-fused pyridoindolone derivatives are obtained in high yields in a relatively short period of time under mild reaction conditions. To the best of our knowledge, this is the first approach where one can synthesize free indole N-H benzo-fused pyridoindolones. Also, both indole and pyridone cores are constructed during the course of the reaction. The methodology shows good functional group tolerance and allows synthesis of thiophene-fused pyridoindolones and fused indolobenzonaphthyridone derivatives.

An indolylquinoline derivative promotes apoptosis in human lung cancer cells by impairing mitochondrial functions.

A number of effective anti-cancer drugs contain either indole or quinoline group. Compounds fused indole and quinoline moieties altogether as indolylquinoline were rarely reported as anti-cancer agents. We reported here that a synthetic indolylquinoline derivative, 3-((7-ethyl-1H-indol-3-yl)-methyl)-2-methylquinoline (EMMQ), inhibited the growth of human non-small cell lung cancer (NSCLC) cells in dose- and time-dependent manners. The cytotoxicity was mediated through apoptotic cell death that began with mitochondrial membrane potential interruption and DNA damage. EMMQ caused transient elevation of p53 that assists in cytochrome c release, cleavage of downstream PARP and procaspase-3 and mitochondria-related apoptosis. The degree of apoptotic cell death depends on the status of tumor suppressor p53 of the target cells. H1299 cells with stable ectopic expression of p53 induced cytotoxicity by disrupting mitochondria functions that differed with those transfected with mutant p53. Knocking-down of p53 attenuated drug effects. EMMQ suppressed the growth of A549 tumor cells in xenograft tumors by exhibiting apoptosis characteristics. Given its small molecular weight acting as an effective p53 regulator in NSCLC cells, EMMQ could be an addition to the current list of lung cancer treatment.

Syntheses of 4-Indolylquinoline Derivatives via Reductive Cyclization of Indolylnitrochalcone Derivatives by Fe/HCl.

An easy and efficient procedure for the synthesis of 4-indolylquinoline derivatives is described. This process involves two steps, the first of which is the Michael addition of indole to nitrochalcones promoted by sulfamic acid under solvent free conditions and the second step is a reductive cyclization of the indolylnitrochalcone intermediates to 4-indolylquinoline derivatives by Fe/HCl in ethanol. In both steps, the reactions are clean and the yields of products are high.

Synthesis of Bicyclic Isoxazoles and Isoxazolines via Intramolecular Nitrile Oxide Cycloaddition.

An efficient and straight forward procedure for the syntheses of bicyclic isoxazole/isoxazoline derivatives from the corresponding dimethyl-2-(2-nitro-1-aryl/alkyl)-2-(prop-2-yn-1yl)malonates or dimethyl 2-allyl-2-(2-nitro-1-aryl/alkyl ethyl)malonate is described. High yields and simple operations are important features of this methodology.

FeCl3 catalyzed regioselective C-alkylation of indolylnitroalkenes with amino group substituted arenes.

An efficient FeCl3 catalyzed protocol for the synthesis of amino functionalized indolylnitroalkanes from easily available precursor indolylnitroalkenes and substituted amines has been developed. Regioselective C-alkylation in the presence of free amino substituted arenes occurred. The scope of this methodology shows good functional group tolerance, and further, this protocol was used to prepare indolylquinoline derivatives.

Molecular iodine-mediated reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts: an easy route to naphthyl ketones and iodo-substituted isochromenes.

The molecular iodine-promoted reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts is reported. In the presence of I2, naphthyl ketone derivatives are produced, whereas in the presence of I2/K3PO4, iodo-substituted isochromene derivatives are produced.

Pd(II)-catalyzed hydroarylations/hydroalkenylations of terminal alkynes: regioselective synthesis of allylic, homoallylic, and 1,3-diene systems.

A Pd-catalyzed regioselective hydroarylation of terminal alkynes containing a heteroatom has been developed via carbopalladation for the synthesis of allylic ethers, amines, and homoallylic alcohols. Moreover, hydroalkenylation of alkynes produces a variety of stereodefined 1,4-dienes with high regioselectivity. The important features of the present protocol are that it is highly regioselective, operationally rapid, and scalable with a huge substrate scope using only 3 mol% of PdCl2(PPh3)2 catalyst in the presence of a mild base KOAc.

Halonium ion mediated synthesis of 2-halomethylene-3-oxoketoxime derivatives from isoxazoline N-oxides.

A protocol for the N-bromosuccinimide (NBS)- and trichloroisocyanuric acid (TCCA)-mediated synthesis of novel 2-halomethylene-3-oxoketoximes via one-pot halogenation/oxidation of isoxazoline N-oxide derivatives is described here. The keto functionality of 3-ketoximes was selectively reduced by lithiumaluminum hydride to synthesize an unprecedented type of Baylis-Hillman oxime, which underwent N-O coupling to produce new isoxazoline N-oxide derivative.

Pd-Catalyzed Regioselective (Markovnikov) Addition of Aryl Boronic Acids to Terminal Alkynes of 1,3-Dicarbonyl Compounds and Cyclization/Debenzoylation of Olefinic Dicarbonyl: Access to Arylated Pyran and (E)-4-Methylene-1,6-diphenylhex-5-en-1-one.

This Letter outlines palladium-catalyzed regioselective (Markovnikov's) addition of aryl boronic acids to propargyl 1,3-dicarbonyl alkyne to accomplish olefinic/diene 1,3-dicarbonyl compounds without the need for water workup. This methodology showcases remarkable performance with wide-ranging substrate diversity, achieving high yields while employing merely 3 mol % [Pd] alongside a mild KOAc base. Moreover, the utility of dicarbonyl olefins is exemplified through their application in intramolecular cyclization and debenzoylation reactions to access valuable trisubstituted pyran building blocks and (E)-4-methylene-1,6-diphenylhex-5-en-1-one synthesis.