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5-(4,5-Dihydro-1H-pyrazol-3-yl)isoxazoles (pyrazoline-isoxazoles) are readily oxidized by active manganese dioxide in benzene or dichloromethane at room temperature. As a result, a simple and efficient method for the synthesis of the corresponding pyrazoleisoxazoles in 94–99% yields was developed. It was shown that 3-ethynyl-1H-pyrazoles are inactive in the 1,3-dipolar cycloaddition reaction with nitrile oxides and nitrile imines. The synthesized di- and trisubstituted pyrazole-isoxazoles showed weaker luminescent properties compared to pyrazoline-isoxazoles. [ABSTRACT FROM AUTHOR]

The first representatives of new fused tricyclic heterosystems, namely 3,3a‐dihydro‐1H‐imidazo[4′,5′:4,5]imidazo[2,1‐b]thiazoles and 3,3a‐dihydro‐1H‐imidazo[4′,5′:4,5]imidazo[2,1‐b][1,3]selenazoles have been synthesized through the regioselective reaction of diethyl acetylenedicarboxylate with semithioglycolurils, thioglycolurils or selenoglycolurils. Study of antifungal properties of the obtained compounds against Venturia inaequalis (V. i.), Rhizoctonia solani (R. s.), Fusarium oxysporum, Fusarium moniliforme, Bipolaris sorokiniana (B. s.) and Sclerotinia sclerotiorum phytopathogenic fungi has been performed. Tested compounds possessed good inhibition activity against R. s., B. s. with 45–94 % by mycelium growth inhibition test method, which were more active than the well–known azole fungicide triadimefon as positive control. The best active thiazole derivative was established to be effective against R. s. (94 %), B.s. (65 %) and V. i. (60 %). Two selenazole derivatives showed good activity with 69 % inhibition against R. s. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive overview of the synthesis and characterization of luminescent substances containing azole motifs, specifically focusing on pyrazole derivatives. The authors explore different synthetic routes and reactions with hydrazines to develop more efficient methods for the synthesis of ethynylpyrazoles and ethynylpyrazolines. They also discuss the potential applications of the synthesized compounds in medicinal, agricultural, and materials science fields. The article includes experimental results, discusses reaction mechanisms, and provides data to support their findings. This resource is valuable for library patrons conducting research on azole compounds and their applications. [Extracted from the article]

Discovering new bonding scenarios and subsequently exploring the reactivity contribute substantially to advance the main group element chemistry. Herein, we report on the isolation and characterization of an intriguing class of the hydrido‐benzosiloles 2–4. These compounds exhibit a side arm of the amidinatosilylenyl group, featuring unidirectional silicon(II)/silicon(IV) donor‐acceptor interaction on account of the geometric constraint. Furthermore, the reactions involving 2–4 with nitriles yield the tricyclic compounds that edge‐fused of the Si‐heteroimidazolidine‐CN2Si2, silole‐C4Si, and phenyl‐C6‐rings (5–13). These compounds are manifesting a unique reaction that the silicon(II)/silicon(IV) interaction enables the enamination of the α‐H‐bearing nitriles. The reaction mechanism involved in H‐shift under oxidative addition at silylene followed by hydrosilylation of a ketenimine intermediate was revealed by density function theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Excited State Intramolecular Proton Transfer (ESIPT), originally discovered and explored in depth in a number of extensive photophysical studies, is more recently rediscovered as a powerful synthetic tool, offering rapid access to complex polyheterocycles. In our prior work we have employed ESIPT in aromatic o-keto amines and amides, leading to diverse primary photoproducts—complex quinolinols or azacanes possessing a fused lactam moiety—which could additionally be modified in short, high-yielding postphotochemical reactions to further grow complexity of the heterocyclic core scaffold and/or to decorate it with additional functional groups. Given that sulfonamides are generally known as privileged substructures, in this study we pursued two goals: (i) To explore whether sulfonamides could behave as proton donors in the context of ESIPT-initiated photoinduced reactions; (ii) To assess the scope of subsequent complexity-building photochemical and postphotochemical steps, which give access to polyheterocyclic molecular cores with fused cyclic sulfonamide moieties. In this work we show that this is indeed the case. Simple sulfonamide-containing photoprecursors produced the sought-after heterocyclic products in experimentally simple photochemical reactions accompanied by significant step-normalized complexity increases as corroborated by the Böttcher complexity scores. [ABSTRACT FROM AUTHOR]

The new polyheterocyclic compound, 2-benzyl-7-(4-chlorophenyl)-3-morpholino-6-((1-phenyl-1H-1,2,3-triazol-4-yl)methyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one, was synthesized by a sequential combination of 4-chlorobenzaldehyde, (1-phenyl-1H-1,2,3-triazol-4-yl)methanamine, 2-isocyano-1-morpholino-3-phenylpropan-1-one, and maleic anhydride under a microwave-assisted one-pot process [Ugi-Zhu/aza Diels-Alder cycloaddition/N-acylation/decarboxylation/dehydration] with a 28% overall yield. The synthesized compound was fully characterized by 1D (1H, 13C) and 2D (COSY, HSQC, and HMBC) NMR, FT-IR, and HRMS. [ABSTRACT FROM AUTHOR]

An expeditious assembling of fused poly‐heterocyclic structures having a N(Acyl), N(aryl)‐Acetal core has been accomplished by cascade reaction of ortho‐functionalized anilines with 2‐formylbenzonitrile and subsequent intramolecular N‐amidic cyclization on different electrophilic carbons. The syntheses have been finalized using both cathodically‐initiated and conventional base‐catalyzed methods and comparing the two approaches in terms of substrate/product scope, efficiency, energy‐saving and sustainability in general. [ABSTRACT FROM AUTHOR]

A diversity-oriented synthesis (DOS) of two new polyheterocyclic compounds was performed via an Ugi-Zhu/cascade (N-acylation/aza Diels-Alder cycloaddition/decarboxylation/dehydration)/click strategy, both step-by-step to optimize all involved experimental stages, and in one pot manner to evaluate the scope and sustainability of this polyheterocyclic-focused synthetic strategy. In both ways, the yields were excellent, considering the high number of bonds formed with release of only one carbon dioxide and two molecules of water. The Ugi-Zhu reaction was carried out using the 4-formylbenzonitrile as orthogonal reagent, where the formyl group was first transformed into the pyrrolo[3,4-b]pyridin-5-one core, and then the remaining nitrile group was further converted into two different nitrogen-containing polyheterocycles, both via click-type cycloadditions. The first one used sodium azide to obtain the corresponding 5-substituted-1H-tetrazolyl-pyrrolo[3,4-b]pyridin-5-one, and the second one with dicyandiamide to synthesize the 2,4-diamino-1,3,5-triazine-pyrrolo[3,4-b]pyridin-5-one. Both synthesized compounds may be used for further in vitro and in silico studies because they contain more than two heterocyclic moieties of high interest in medicinal chemistry, as well as in optics due to their high π-conjugation. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed tandem cyclization reaction was developed, which offers a pragmatic synthesis of aminated tetracyclic 1,2-benzothiazepine 1-oxides bearing a highly fused medium-sized cyclic unit. An acetyl (Ac) group was found to be the optimal protecting group for sulfoximines to reduce the nucleophilic ability of the N atom, thus efficiently suppressing the formation of intramolecular 5- exo - dig cyclization side products. The transformation proceeds through a double syn -carbopalladation/annulation sequence to construct the rigid tetracyclic carbo-heterocyclic framework with excellent chemoselectivity and regioselectivity. [ABSTRACT FROM AUTHOR]

The new polyheterocyclic compound, 2-benzyl-7-(4-chlorophenyl)-3-morpholino-6-((1-phenyl-1H-1,2,3-triazol-4-yl)methyl)-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one, was synthesized by a sequential combination of 4-chlorobenzaldehyde, (1-phenyl-1H-1,2,3-triazol-4-yl)methanamine, 2-isocyano-1-morpholino-3-phenylpropan-1-one, and maleic anhydride under a microwave-assisted one-pot process [Ugi-Zhu/aza Diels-Alder cycloaddition/N-acylation/decarboxylation/dehydration] with a 28% overall yield. The synthesized compound was fully characterized by 1D (1H, 13C) and 2D (COSY, HSQC, and HMBC) NMR, FT-IR, and HRMS.

A two-step approach to rapidly access a diverse array of pyrido[2,1- a ]isoindol-5-ium salts from 2-pyridinylstyrenes through an unprecedented pyridinyl group mediated metal-free Wacker-type oxidation and an acid-mediated cyclization has been developed. As a part of the mechanistic investigation of this novel Wacker-type oxidation, the abnormal instability and reactivity of the pyrido[2,1- a ]isoindole intermediates were studied through DFT calculations. [ABSTRACT FROM AUTHOR]

A base‐catalyzed novel [3+2] cycloaddition reaction between arylidene‐1‐phenyl succinimides and alkylidene acenaphthylenones is carried out to access succinimide substituted spiro[acenaphthylenone‐cyclopentane]fused scaffolds with high regio‐ and stereo‐selectivity under mild conditions. The reaction of alkylidene acenaphthylenones with 1,4‐benzoxazinone derivatives under the influence of environmentally benign iodine afforded polyheterocyclic compounds embedded with pyrrole moiety. This metal‐free synthesis is highly efficient and atom economic and the protocol obviates column chromatography. The products are isolated by simple decantation followed by washing with solvent. [ABSTRACT FROM AUTHOR]

Seven new pyrrolo[3,4- b ]pyridin-5-ones linked to a meso -thienyl BODIPY moiety by an ethynylbenzene π-conjugated system were synthesized in one-pot manner via an Ugi-Zhu reaction coupled to a cascade process [ aza Diels-Alder cycloaddition/ N -acylation/decarboxylation/dehydration]. The photophysical properties of the polyheterocyclic compounds were evaluated by UV–Vis and fluorescence spectroscopy in five solvents of different polarities. All synthesized products showed two distinct absorption/emission bands, corresponding to both fluorophores separately. The fluorescence intensity of the pyrrolo[3,4- b ]pyridin-5-one was the highest in toluene, and it decreased with increasing solvent polarity. On the other hand, the fluorescence intensity of the meso -thienyl BODIPY fragment was insensitive to solvent polarity. The effect of different substituents bonded to the pyrrole ring was evaluated, finding that strong electron-donating groups influence the fluorescence intensity and decay rate of the compounds, even with the presence of a methylene spacer. Moreover, the electronic structure was assessed by DFT and TD-DFT calculations, which reproduced the experimental results reasonably well, showing that the HOMO is located on the pyrrolo[3,4- b ]pyridin-5-one core, while the LUMO is on the BODIPY fragment. [Display omitted] [ABSTRACT FROM AUTHOR]

Excited State Intramolecular Proton Transfer (ESIPT), originally discovered and explored in depth in a number of extensive photophysical studies, is more recently rediscovered as a powerful synthetic tool, offering rapid access to complex polyheterocycles. In our prior work we have employed ESIPT in aromatic o-keto amines and amides, leading to diverse primary photoproducts—complex quinolinols or azacanes possessing a fused lactam moiety—which could additionally be modified in short, high-yielding postphotochemical reactions to further grow complexity of the heterocyclic core scaffold and/or to decorate it with additional functional groups. Given that sulfonamides are generally known as privileged substructures, in this study we pursued two goals: (i) To explore whether sulfonamides could behave as proton donors in the context of ESIPT-initiated photoinduced reactions; (ii) To assess the scope of subsequent complexity-building photochemical and postphotochemical steps, which give access to polyheterocyclic molecular cores with fused cyclic sulfonamide moieties. In this work we show that this is indeed the case. Simple sulfonamide-containing photoprecursors produced the sought-after heterocyclic products in experimentally simple photochemical reactions accompanied by significant step-normalized complexity increases as corroborated by the Böttcher complexity scores.

Dearomative cycloadditions offer rapid access to complex 3D molecular architectures, commonly via a sp2-to-sp3 rehybridization of two atoms of an aromatic ring. Here we report that the 6e π-system of a benzenoid aromatic pendant could be exhaustively depleted within a single photochemical cascade. An implementation of this approach involves the initial dearomative [4+2] cycloaddition of the Exited State Intramolecular Proton Transfer (ESIPT)-generated azaxylylene, followed by two consecutive [2+2] cycloadditions of auxiliary π moieties strategically positioned in the photoprecursor. Such photochemical cascade fully dearomatizes the benzenoid aromatic ring, saturating all six sp2 atoms to yield a complex sp3-rich scaffold with high control of its 3D molecular shape, rendering it a robust platform for rapid systematic mapping of underexplored chemical space. Significant growth of molecular complexity - starting with a modular synthesis of photoprecursors from readily available building blocks - is quantified by Böttcher score calculations., (© 2024 Wiley‐VCH GmbH.)

A diversity-oriented synthesis (DOS) of two new polyheterocyclic compounds was performed via an Ugi-Zhu/cascade (N-acylation/aza Diels-Alder cycloaddition/decarboxylation/dehydration)/click strategy, both step-by-step to optimize all involved experimental stages, and in one pot manner to evaluate the scope and sustainability of this polyheterocyclic-focused synthetic strategy. In both ways, the yields were excellent, considering the high number of bonds formed with release of only one carbon dioxide and two molecules of water. The Ugi-Zhu reaction was carried out using the 4-formylbenzonitrile as orthogonal reagent, where the formyl group was first transformed into the pyrrolo[3,4-b]pyridin-5-one core, and then the remaining nitrile group was further converted into two different nitrogen-containing polyheterocycles, both via click-type cycloadditions. The first one used sodium azide to obtain the corresponding 5-substituted-1H-tetrazolyl-pyrrolo[3,4-b]pyridin-5-one, and the second one with dicyandiamide to synthesize the 2,4-diamino-1,3,5-triazine-pyrrolo[3,4-b]pyridin-5-one. Both synthesized compounds may be used for further in vitro and in silico studies because they contain more than two heterocyclic moieties of high interest in medicinal chemistry, as well as in optics due to their high π-conjugation.

A highly efficient approach to a new indolizine scaffold fused with pyrrolo[1,2-c]pyrimidine was achieved via one-pot three-component coupling followed by an oxidative cyclization reaction. The simple two-step sequence allowed rapid access to various tetracyclic compounds from commercially available starting materials with the formation of five new bonds. Here, we observed the effects of these compounds on cell viability in HepG2, H1299, HT29, AGS, and A549 cancer cell lines. Interestingly, this fused scaffold had more potent anticancer activity in hepatocellular carcinoma HepG2 and Huh7 cells than other cancer cells. In particular, 5r strongly decreased cell viability in HepG2 and Huh7 cells with an IC50 value of 0.22 ± 0.08 and 0.10 ± 0.11 µM, respectively, but had a very weak inhibitory effect on the cell viability of other cancer cell lines. In addition, 5r significantly inhibited cell migration and induced apoptosis in HepG2 and Huh7 cells via the activation of caspase-3 and cleavage of PARP in a dose-dependent manner. Notably, the co-treatment of 5r with gemcitabine resulted in the significant additional inhibition of cell viability in HepG2 and Huh7 cells. Our results suggest that 5r could be used to develop new chemotype anticancer agents against liver cancers.

The present review is focused on the main transformation routes of sp2- and sp3-hybridized carbanions derived from the compounds containing two or more fused N,O,S-heterocycles. The rearrangement and fragmentation reactions and their applications in the synthesis of poorly available organic compounds are discussed. In the review, separate consideration is given to the reactions leading to a decrease, retention, and increase in the number of annulated heterocycles. [ABSTRACT FROM AUTHOR]

An expedient one-pot sequential five component synthesis of highly substituted pyrazolo-N-methyl-piperidine grafted spiro-indenoquinoxaline pyrrolidine heterocycles involving [3 + 2]-cycloaddition of azomethine ylides as the key step is described. The protocol provides a mild reaction condition, high yield of the products, high regioselectivity and operational simplicity to assemble complex structural entity in a single operation. The structure of the product was confirmed by spectroscopic techniques and elemental analysis. [ABSTRACT FROM AUTHOR]

The synthesis of five new bis-furanyl-pyrrolo[3,4-b]pyridin-5-ones in 30 to 40% yields through a domino sequence based on the Ugi-Zhu three-component reaction is described. Then, on the main protease MPro (PDB: 6lu7) from the SARS-CoV-2, the synthesized products and co-crystallized ligands of MPro were in silico evaluated using the docking technique, finding moderate to good binding energies and some interesting interactions, demonstrating that the ligand 8c can be considered as a drug candidate against the SARS-CoV-2-MPro due to its LE value (−5.96 kcal/mol), which is better than other synthesized and reported molecules in the literature. At the same time, hydrophobic interactions play a crucial role in the ligand target molecular couplings, demonstrated through a hydrophobicity surfaces analysis. Finally, 8a and 8b can also be considered as drug candidates. Thus, some synthesized bis-furanyl-pyrrolo[3,4-b]pyridin-5-ones may be used for further in vitro assays against the virus.

A simple and efficient one-pot synthesis of novel polyheterocyclic benzimidazo[1,2-a]-chromeno[4,3-d]pyrimidinones 4 via a three-component condensation of 2-aminobenzimidazole 1, aromatic aldehydes 2 and 4-hydroxy coumarin 3 catalyzed by Bronsted acid ionic liquid triethyl ammonium hydrogen sulphate [Et3NH][HSO4] under solvent-free conditions is reported. The main advantages of this protocol are short reaction time, easy work-up, operational simplicity, and excellent yields with high purity, without intervention of chromatography. [ABSTRACT FROM AUTHOR]

A simple and efficient one-pot synthesis of novel polyheterocyclic benzimidazo[1,2-a]-chromeno[4,3-d]pyrimidinones 4 via a three-component condensation of 2-aminobenzimidazole 1, aromatic aldehydes 2 and 4-hydroxy coumarin 3 catalyzed by Bronsted acid ionic liquid triethyl ammonium hydrogen sulphate [Et3NH][HSO4] under solvent-free conditions is reported. The main advantages of this protocol are short reaction time, easy work-up, operational simplicity, and excellent yields with high purity, without intervention of chromatography. [ABSTRACT FROM AUTHOR]

A collection of 2‐aryl‐3‐vinylimidazo[1,2‐a]pyridines, substituted on the pyridine ring and/or the aryl substituent, can be obtained by reaction of 2‐aminopyridines with properly substituted nitrobutadienes, originated by an initial ring opening of a nitrothiophenic precursor. Although the aza‐Michael addition of 2‐aminopyridine on a nitrovinyl moiety is the starting point of classic approaches to imidazopyridines, the final structures generated herein are the result of a cascade process made possible by the particular functionalization on the conjugated systems. Beside the general interest inherent to the pharmacologically versatile imidazo[1,2‐a]pyridine structural motif, the substituents present in the obtained compounds allow specific synthetic elaboration to e. g. polycyclic fluorescent heterocycles. [ABSTRACT FROM AUTHOR]

An unprecedented l-proline-mediated one-pot sequential synthesis of novel 3,10-diphenyl-2,3,4,9,10,11-hexahydronaphtho[1,2-e:4,3-e′]bis[1,3]oxazine derivatives from 2,3-dihydroxynaphthalene, formaldehyde, and anilines under solvent-free conditions has been reported. Under the optimized reaction conditions, a broad range of substituted anilines and 2,3-dihydroxynaphthalene were found to participate in this transformation, thus affording new 3,10-diphenyl-2,3,4,9,10,11-hexahydronaphtho[1,2-e:4,3-e′]bis[1,3]oxaz-ines in good to excellent yields. This green procedure offers several advantages such as high atom economy, mild reaction conditions, short reaction time, easy workup and column chromatography-free method with a wide range of functional group tolerance. [ABSTRACT FROM AUTHOR]

In this work, we continue our adventure in the chemistry of 5-5 tri-nitrogen bicycles. We disclose herein a one-step reaction to synthesize 1 H -imidazo[1,5- a ]imidazoles with different substituents introduced through the use of a wide range of aldehydes and isocyanides by using a Groebke–Blackburn–Bienaymé multicomponent reaction. The aim is to build a new library of 1 H -imidazo[1,5- a ]imidazole scaffolds. This bicycle was then modified to access new nitrogen-containing polycyclic compounds. [ABSTRACT FROM AUTHOR]

An unprecedented metal‐free approach to polyheterocycles bearing furoquinoline and C2‐maleimide‐substituted quinoline has been developed with easily available quinoline N‐oxides and maleimides via tandem reactions mediated by I2, including iodization, [3+2] cycloaddition and nucleophilic addition reactions. I2 acts as a halogenating agent to promote the subsequent [1,5]‐sigma rearrangement. Two C−O bonds, three C−C bonds and a quaternary carbon center were formed in "one pot" manner. [ABSTRACT FROM AUTHOR]

New aspects of multicomponent condensation reactions of ethylene/propylenediamine, formaldehyde and unsubstituted and 1-methyl substituted semithio- and dithioglycolurils have been examined. Ethylene-linked 2,3a,4a,6,9,10a,11aheptaaza-6,9-methanobenzo cd cyclonona gh pentalene and 2,6:10,14-dimethano-2,6,7a,8a,10,14,15a,16a-octaazadicyclodeca cd , gh pentalene as well as their simpler analogues were synthesized, and their structures were proved by 1D and 2D NMR spectroscopy, HRMS and X-ray analysis. [ABSTRACT FROM AUTHOR]

We developed an enantioselective organocascade Michael/ Henry reaction in the presence of a bifunctional organocatalyst to construct chiral polyfunctionalized 3,4-dihydro-2H-thiopyrano[2,3- b]quinolines. The resulting optically active products with three contiguous stereocenters, one quaternary and two tertiary, were obtained in moderate to good yields and with good to excellent enantioselectivities. Remarkably, the resulting products were readily converted into polyfunctionalized optically active furo[2',3':4,5]thiopyrano[2,3- b]quinoline, 3,4-dihydro-2H-thiopyrano[2,3-b]quinoline 1-oxide and 2,3-dihydro-4H-thiopyrano[2,3-b]quinolin-4-one derivatives. [ABSTRACT FROM AUTHOR]

Polyheterocycle construction with high diastereoselectivity by utilizing a radical process is still problematic. In this communication, a silver-catalyzed carbon-phosphorus functionalization for polyheterocycle formation is described that furnishes good diastereoselectivity. Various substituted 1-(1 H-indol-1-yl)-3-phenylprop-2-en-1-ones and phosphine oxides were suitable for this transformation. This work avoids the installation of direct functional groups and thus makes full use of shorter and more efficient synthetic processes. Preliminary mechanistic investigations indicate that phosphorus radicals are involved by attacking the α-position of α,β-unsaturated carbonyl compounds to generate the desired products. [ABSTRACT FROM AUTHOR]

2-(2-Chloroquinolin-3-yl)-3-(arylamino)-2,3-dihydroquinazolin-4(1 H)-one was converted to quinolino[2′,3′:3,4]pyrazolo[5,1- b]quinazolin-8(6 H)-ones in the presence of KO tBu in DMSO at room temperature. The present method has the advantages of easy conditions, construction of highly novel five heterocycles, transition metal-free conditions, cascade dehydrogenation and intramolecular N-arylation and good to high yield of products. [ABSTRACT FROM AUTHOR]

A new method was developed for the photoinduced dearomatization of arenes through an intramolecular cycloaddition with aza- o-xylylenes generated by excited-state intramolecular proton transfer (ESIPT) in the readily available photoprecursors. The [2+4] topology of this cycloaddition is unprecedented for photo-dearomatizations of benzenoid aromatic carbocycles. It provides rapid access to novel heterocycles, cyclohexadieno-oxazolidino-quinolinols, as valuable synthons for a broad range of post-photochemical transformations. [ABSTRACT FROM AUTHOR]

Fluorescence-based technologies play a pivotal role in various biomedical applications. Here we report an efficient route to a new class of fluorophores, indolizino[3,2-c]quinolines, via the oxidative Pictet-Spengler cyclization strategy. The condensation of several 2-methylpyridines with 2-bromo-2'-nitroacetophenone allowed for the rapid assembly of indolizines with a 2-nitrophenyl group at the C2 position. The subsequent reduction of the nitro group under mild conditions followed by oxidative Pictet-Spengler cyclization with various aryl aldehydes in the presence of a catalytic amount of FeCl3 furnished the indolizino[3,2-c]quinolines in good overall yields. We also examined the photophysical properties of this new series of polyheterocyclic compounds. Several indolizino[3,2-c]quinolines were found to have unique and desirable optical properties, suggesting that these compounds may be suitable for use as prospective fluorescent probes in aqueous systems. [ABSTRACT FROM AUTHOR]

A highly efficient approach to a new indolizine scaffold fused with pyrrolo[1,2- c ]pyrimidine was achieved via one-pot three-component coupling followed by an oxidative cyclization reaction. The simple two-step sequence allowed rapid access to various tetracyclic compounds from commercially available starting materials with the formation of five new bonds. Here, we observed the effects of these compounds on cell viability in HepG2, H1299, HT29, AGS, and A549 cancer cell lines. Interestingly, this fused scaffold had more potent anticancer activity in hepatocellular carcinoma HepG2 and Huh7 cells than other cancer cells. In particular, 5r strongly decreased cell viability in HepG2 and Huh7 cells with an IC 50 value of 0.22 ± 0.08 and 0.10 ± 0.11 µM, respectively, but had a very weak inhibitory effect on the cell viability of other cancer cell lines. In addition, 5r significantly inhibited cell migration and induced apoptosis in HepG2 and Huh7 cells via the activation of caspase-3 and cleavage of PARP in a dose-dependent manner. Notably, the co-treatment of 5r with gemcitabine resulted in the significant additional inhibition of cell viability in HepG2 and Huh7 cells. Our results suggest that 5r could be used to develop new chemotype anticancer agents against liver cancers.

A sequential one-pot protocol for the synthesis of indole-based peri-annulated polyheterocycles using trifluoroacetic acid and a gold-silver combined catalyst system is described. The reac-tion is thought to proceed via an imine formation-cationic n-cycli-zation-alkyne activation-intramolecular hydroamination sequence to yield novel dihydrobenzo[6,7]indolo[3',4':3,4,5]azepino[2,1-a]isoquinolines in good yields. [ABSTRACT FROM AUTHOR]

An efficient, one-pot synthetic approach to precursors of some new aminochromene/xanthene annulated heterocycles via a tetrabutylammonium hydrogen sulfate–mediated intramolecular domino Knoevenagel–hetero-Diels–Alder reaction is described. The method is general and efficient. The stereochemistry of the product was confirmed by various NMR experiments and single-crystal x-ray diffraction data. Supplemental materials are available for this article. Go to the publisher's online edition ofSynthetic Communications® to view the free supplemental file. [ABSTRACT FROM PUBLISHER]

Abstract: Simple synthetic strategies for the hitherto unreported [1,2,4]triazolo[4,3-a]pyrido[4,3-d]pyrimidines 8 and [1,2,4]triazolo[4′,3′:1,2]pyrimido[4,5-b][1,6]naphthyridine-5-one 15 are described based on reaction of thione 3 and 12 with hydrazonoyl chloride 1a–h, respectively. The structures of products 8 and 15 were confirmed by spectroscopic and X-ray crystallographic analyses. Also, the mechanism of such reactions was discussed. In addition, reaction of compound 12 with bromoacetic acid and hydrazine hydrate was investigated. Compounds were screened against 5α-reductase and showed activities with good LD50 and LD90 for all compounds. [ABSTRACT FROM AUTHOR]

The review article represents a survey covering the synthetic strategies leading to benzimidazolebased fused polyheterocyclic systems utilizing simple reactive benzimidazole synthons since 1980. The polyheterocyclic systems are classified based on the number of rings; tetra-, penta-, hexa- and hepta-fused ring systems. Among each polyheterocyclic system, further classification according to the number of heterotoms; two-, three-, four-, five-, six- and seven heteroatoms is considered. [ABSTRACT FROM AUTHOR]

Abstract: An efficient and rapid synthesis of furo[3,2-b]pyridine 1 is described using a one-pot Sonogashira coupling/heteroannulation sequence. Regioselective lithiation of this synthon was performed leading to various 2-substituted furo[3,2-b]pyridines. Some of them were used as substrates for short functional synthesis of polyheterocycles. [Copyright &y& Elsevier]

A number of quinolone-annulated pentacycles have been regioselectively synthesized in 90-95% yields by sequential Claisen rearrangements. The second synthesis is anhydrous AlCl3-catalyzed charge-accelerated aromatic Claisen rearrangement of 1-aryloxymethyl-6-alkyl-3H-pyrano[2,3-c]quinolin-5(6H)-ones in dichloromethane at rt for 5-10 min. The precursors were synthesized by the thermal [3,3]-sigmatropic rearrangement of the corresponding ethers. [ABSTRACT FROM AUTHOR]

Several coumarin-annulated polyheterocycles have been regioselectively synthesized in 82-90% yield by anhydrous AlCl3-catalyzed charge-accelerated Claisen rearrangement of 4-aryloxymethyl [3,2-c] pyrano benzopyran-5-ones in dichloromethane at rt for 0.5 h. [ABSTRACT FROM AUTHOR]

The main path in the mass-spectral dissociation of the hetaryl analogs of unsymmetrical benzoins is β-fragmentation with cleavage of the central C-C bond. Here, the strongest peak in the mass spectra of α-benzoins is the peak of the hydroxymethylhetaryl cation, and in β-benzoins it is the peak of the hetaroyl cation. The thermal α → β isomerization of the hetaryl analogs of benzoin was studied. In the case of indole and pyrrole derivatives the formation of polyheterocyclic systems is observed. [ABSTRACT FROM AUTHOR]

Abstract: A review is presented on those polymers which contain diphenylsilylene units and 1,3,4-oxadiazole rings either in the main chain or in the pendent groups. The synthesis of silicon-containing monomers as well as of the polyoxadiazoles based on them is described. The properties of these polymers, such as solubility, film forming ability, thermal stability, electrochemical behavior and photoluminescence properties, and their potential applications are discussed. [Copyright &y& Elsevier]

• N -Propargyl 2-(imidazole-2-yl)indoles were investigated in cyclization reactions. • Zn(OTf) 2 -catalyzed reaction gave cyclization product at C-3 of the indole nucleus. • Base-promoted reaction led to cyclization at N-1 of indole. • The use of 3-aryl propargylamines gave a cascade cyclization. The cyclization reactions of 2-(N -propargyl)imidazole-2-yl)indoles (synthesized via the hydroamination reaction between N -propargyl indole-2-carboxamides and propargylamine) have been investigated under Lewis acid- and base-promoted conditions. The polyheterocyclic compounds thus obtained were shown to possess promising photophysical properties. [ABSTRACT FROM AUTHOR]

• Chromeno pyrimido[1,2- b ]indazolone was synthesized from one-pot reactions. • The reactions are undergoing in solvent-free conditions. • Broad substrate scope and good functional compatibility. • Excellent yield and column chromatography-free are the main advantage of this method. A convenient and highly efficient method for the synthesis of novel polyheterocyclic chromeno pyrimido[1,2 -b ]indazolone derivatives via a three-component condensation of 1H -indazol-3-amine, aldehydes and 4-hydroxycoumarin catalyzed by Bronsted acid ionic liquid [Et 3 NH][HSO 4 ] under solvent-free reaction conditions is presented. This ionic liquid is air and water stable and easy to prepare from amine and acid. The main advantages of this protocol includes short reaction time, excellent yield, easy work-up, operational simplicity, a wide range of functional group tolerance and column chromatography-free method. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields. [ABSTRACT FROM AUTHOR]