Articles de revues : « Carbocyclic ring compounds »

1

Yavari, Issa, et Aliyeh Khajeh-Khezri. « Recent Advances in the Synthesis of Hetero- and Carbocyclic Compounds and Complexes Based on Acenaphthylene-1,2-dione ». Synthesis 50, n^o 20 (16 août 2018) : 3947–73. http://dx.doi.org/10.1055/s-0037-1610209.

Texte intégral

Résumé :

Acenaphthylene-1,2-dione has been utilized in a wide range of reactions as a starting material for the synthesis of hetero- and carbocyclic compounds and complexes. This review provides a short summary of the recent advances in the application of acenaphthylene-1,2-dione in the synthesis of hetero- and carbocyclic systems and bioactive compounds. In addition, the applications of acenaphthylene-1,2-dione in the synthesis of spiro compounds, propellanes, and ligands in catalyst reactions, from 2002 to early 2018, are included.1 Introduction2 Synthesis of Spiro Compounds Employing Acenaphthylene-1,2-dione2.1 Methods for the Construction of Spiro Compounds2.1.1 By 1,3-Dipolar Cycloaddition of Acenaphthylene-1,2-dione via Azomethine Ylides2.1.2 By Multicomponent Reactions of Acenaphthylene-1,2-dione with C–H Acidic Compounds2.1.3 By Reaction of Acenaphthylene-1,2-dione with Zwitterionic Intermediates2.1.4 By Substitution and Multicomponent Reactions of Acenaphth- ylene-1,2-dione with Different Nucleophiles3 Synthesis of Propellanes by Employing Acenaphthylene-1,2-dione3.1 Methods for the Construction of Propellanes Based on Acenaph- thylene-1,2-dione3.1.1 By Reaction of Acenaphthylene-1,2-dione with Nucleophiles3.1.2 By Reaction of Acenaphthylene-1,2-dione with Binucleophiles4 Synthesis of Ligands Employing Acenaphthylene-1,2-dione for Catalyst Reactions5 Synthesis of Novel Hetero- and Carbocyclic Compounds Employing Acenaphthylene-1,2-dione5.1 By Reaction of Acenaphthylene-1,2-dione with Nucleophiles5.2 By Reaction of Acenaphthylene-1,2-dione with Zwitterionic Intermediates5.3 By Ring Opening and Ring Enlargement6 Conclusion

Styles APA, Harvard, Vancouver, ISO, etc.

2

Lautens, Mark, Dino Alberico, Cyril Bressy, Yuan-Qing Fang, Brian Mariampillai et Thorsten Wilhelm. « Palladium-catalyzed ring-forming reactions : Methods and applications ». Pure and Applied Chemistry 78, n^o 2 (1 janvier 2006) : 351–61. http://dx.doi.org/10.1351/pac200678020351.

Texte intégral

Résumé :

Several Pd-catalyzed cyclization methods were developed, including norbornene-mediated Catellani-type reactions, a Pd-catalyzed coupling reaction of aryl iodides and allyl moieties, and a tandem C-N/C-C coupling of gem-dihalovinyl systems. These ring-forming methods were applied to the synthesis of highly functionalized carbocyclic and heterocyclic compounds. Intermolecular Pd-catalyzed methods for synthesis of highly substituted arene compounds were also developed.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Banwell, MG. « New Methods for the Synthesis of Troponoid Compounds ». Australian Journal of Chemistry 44, n^o 1 (1991) : 1. http://dx.doi.org/10.1071/ch9910001.

Texte intégral

Résumé :

The ring expansion of 7-halogenobicyclo[4.1.0] heptenones and related compounds provides a useful new method for the preparation of the seven-membered conjugated carbocyclic compounds known as tropones and tropolones. This methodology has been exploited in the synthesis of various biologically active troponoid natural products including nezukone, the thujaplicins, thujaplicinol, MY3-469 and colchicine.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Saborit, Gisela V., Carlos Cativiela, Ana I. Jiménez, Josep Bonjoch et Ben Bradshaw. « Synthesis of cis-hydrindan-2,4-diones bearing an all-carbon quaternary center by a Danheiser annulation ». Beilstein Journal of Organic Chemistry 14 (9 octobre 2018) : 2597–601. http://dx.doi.org/10.3762/bjoc.14.237.

Texte intégral

Résumé :

A straightforward synthetic entry to functionalized hydrindane compounds based on a rapid assembly of the core nucleus by a Danheiser cycloaddition is reported. Valuable bicyclic building blocks containing the fused five and six-membered carbocyclic ring system can be achieved in only four steps from a simple acyclic β-keto ester.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Halliday, Jill I., Mary Chebib et Malcolm D. McLeod. « Synthesis and Biological Evaluation of a New Family of Constrained Azabicyclic Homocholine Analogues ». Australian Journal of Chemistry 63, n^o 5 (2010) : 808. http://dx.doi.org/10.1071/ch10024.

Texte intégral

Résumé :

A family of constrained acylated homocholine analogues have been synthesized, based on the azabicyclic ring scaffold derived from a double-Mannich annulation of cyclic ketones. The short synthetic route allows generation of structural diversity including, variation in the carbocyclic ring size, bridgehead substitution, nitrogen substitution and the ester sidechain. Biological assays on selected analogues demonstrate these compounds are nicotinic acetylcholine receptor (nAChR) antagonists. Several analogues also bind to other neuronal transporter and receptor targets.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Mikaia, Anzor. « Protocol for structure determination of unknowns by EI mass spectrometry. II. Diagnostic ions in one ring alicyclic, heterocyclic, and aromatic compounds ». Journal of Physical and Chemical Reference Data 52, n^o 2 (1 juin 2023) : 021501. http://dx.doi.org/10.1063/5.0140771.

Texte intégral

Résumé :

Electron ionization (EI) mass spectra of saturated carbocyclic hydrocarbons containing a single ring with three or more members are discussed followed by the examination of their unsaturated analogs, including aromatic hydrocarbons. Mass spectrometry characteristics of heterocyclic compounds for each cycle size with one, two, three, and more hetero-atoms in a ring are considered along with their mono- and polyunsaturated analogs. An effect of the (a) size of a cycle; (b) number, nature, and location of elements in a ring; (c) position and nature of ring substituents; and (d) nature and location of unsaturation on the dissociation is revealed. Characteristic dissociation directions of these compounds and diagnostically important ions in their spectra are identified. Basic dissociation rules for alicyclic, heterocyclic, and aromatic compounds under EI are established for further use in the analysis of complex chemicals containing these structural elements.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Sivakrishna, Balija, Sehbanul Islam, Amarendra Panda, Maddi Saranya, Manas K. Santra et Shantanu Pal. « Synthesis and Anticancer Properties of Novel Truncated Carbocyclic Nucleoside Analogues ». Anti-Cancer Agents in Medicinal Chemistry 18, n^o 10 (23 janvier 2019) : 1425–31. http://dx.doi.org/10.2174/1871520618666180322120533.

Texte intégral

Résumé :

Background: Modified nucleosides established a prime role as therapeutic drugs. Objective: Design and synthesis of novel truncated carbocyclic nucleoside with modified nucleobases and evaluation of their anticancer properties. Methods: Novel truncated carbocyclic nucleoside analogues were synthesized from a versatile starting material D-ribose. The synthetic route includes stereoselective Grignard reaction, Wittig olefination, ring closing metathesis, double bond hydrogenation and Mitsunobu nucleobase condensation as the key steps. Cytotoxicity was measured using MTT assay in breast cancer cell lines (MCF7 and MDA-MB-231), ovarian cancer cell lines (IGROV1 and OVCAR8). Result & Conclusion: The synthesized compounds were characterized using spectroscopy techniques. The synthesized compounds induced cytotoxicity in breast cancer cell lines (MCF7 and MDA-MB-231), ovarian cancer cell lines (IGROV1 and OVCAR8) while minimal effect on primary cell line. Among the eight analogues, 1b and 1d showed the highest cytotoxicity effect and induced autophagy mode of cell death. These compounds induced autophagy by inactivating AKT and mTOR pathway. In addition, PARP1 was found to be stabilized upon treatment with compound 1b and 1d and is one of the known markers associated with induction of autophagy through the AMPK/mTOR pathway after DNA damage. Taken together, these results suggest that compounds 1b and 1d inhibit cancer cell proliferation through mTOR inactivation-mediated induction of autophagy.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Takahashi, Hidetoshi, Kazuhiro Yoshida et Akira Yanagisawa. « Synthesis of Carbocyclic Aromatic Compounds Using Ruthenium-Catalyzed Ring-Closing Enyne Metathesis ». Journal of Organic Chemistry 74, n^o 10 (15 mai 2009) : 3632–40. http://dx.doi.org/10.1021/jo900456g.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

9

Paquette, Leo A. « Book Review, Carbocyclic Three-Membered Ring Compounds, Houben-Weyl, Methods of Organic Chemistry ». Synthesis 1998, n^o 02 (février 1998) : 225. http://dx.doi.org/10.1055/s-1998-4511.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

10

Paquette, Leo A. « Book Review, Carbocyclic Four-Membered Ring Compounds, Houben-Weyl, Methods of Organic Chemistry ». Synthesis 1998, n^o 02 (février 1998) : 226. http://dx.doi.org/10.1055/s-1998-4512.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

11

Liboska, Radek, Milena Masojídková et Ivan Rosenberg. « Carbocyclic Phosphonate-Based Nucleotide Analogs Related to PMEA. I. Racemic trans-Configured Derivatives ». Collection of Czechoslovak Chemical Communications 61, n^o 2 (1996) : 313–32. http://dx.doi.org/10.1135/cccc19960313.

Texte intégral

Résumé :

Racemic trans-N-(2-phosphonomethoxycycloalkyl) derivatives of heterocyclic bases, a novel type of nucleotide analogs related to 9-(2-phosphonomethoxyethyl)adenine (PMEA), are reported. The synthesis of fully protected adenine- (5), hypoxanthine- (7), guanine- (11), thymine- (13), uracil- (16) and cytosine-containing (18) carbocyclic nucleotide analogs is based on the reaction of trans-2-hydroxycycloalkyl derivatives of N-protected nucleobases (2, 10, 12, 14, 17) with diisopropyl tosyloxymethanephosphonate. Deprotection of these compounds afforded the title nucleotide analogs. The starting nucleoside derivatives have been prepared via nucleophilic oxirane ring opening of cycloalkene oxides with various protected or free nucleobases.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Hwu, Jih Ru, et John M. Wetzel. « Silicon-promoted ring contractions in the formation of carbocyclic spiro compounds. Total synthesis of (-)-solavetivone ». Journal of Organic Chemistry 57, n^o 3 (janvier 1992) : 922–28. http://dx.doi.org/10.1021/jo00029a025.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

13

Liu, Wei, Wenjun Zhang, Hongbo Jin, Qingbo Zhang, Yuchan Chen, Xiaodong Jiang, Guangtao Zhang et al. « Genome Mining of Marine-Derived Streptomyces sp. SCSIO 40010 Leads to Cytotoxic New Polycyclic Tetramate Macrolactams ». Marine Drugs 17, n^o 12 (25 novembre 2019) : 663. http://dx.doi.org/10.3390/md17120663.

Texte intégral

Résumé :

Polycyclic tetramate macrolactams (PTMs) biosynthetic gene cluster are widely distributed in different bacterial types, especially in Streptomyces species. The mining of the genomic data of marine-derived Streptomyces sp. SCSIO 40010 reveals the presence of a putative PTM-encoding biosynthetic gene cluster (ptm′ BGC) that features a genetic organization for potentially producing 5/5/6 type of carbocyclic ring-containing PTMs. A fermentation of Streptomyces sp. SCSIO 40010 led to the isolation and characterization of six new PTMs 1–6. Comprehensive spectroscopic analysis assigned their planar structures and relative configurations, and their absolute configurations were deduced by comparing the experimental electronic circular dichroism (ECD) spectra with the reported spectra of the known PTMs. Intriguingly, compounds 1–6 were determined to have a trans-orientation of H-10/H-11 at the first 5-membered ring, being distinct from the cis-orientation in their known PTM congeners. PTMs 1–5 displayed cytotoxicity against several cancer cell lines, with IC50 values that ranged from 2.47 to 17.68 µM.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Yan, Ning, Yongmei Du, Xinmin Liu, Hongbo Zhang, Yanhua Liu et Zhongfeng Zhang. « A Review on Bioactivities of Tobacco Cembranoid Diterpenes ». Biomolecules 9, n^o 1 (16 janvier 2019) : 30. http://dx.doi.org/10.3390/biom9010030.

Texte intégral

Résumé :

Cembranoids are carbocyclic diterpenes comprising four isoprene units and are natural products with a parent skeleton consisting of a 14-membered ring. They have gained wide interest in recent years and are a major hotspot in the research of natural product chemistry. Since 1962, various tobacco cembranoid diterpenes have been identified. This review systematically discusses and summarises the excellent antimicrobial, insecticidal, cytotoxic and neuroprotective activities of tobacco cembranoid diterpenes. These compounds show potential to be developed as botanical fungicides, cytotoxic drugs and drugs for the treatment of human immunodeficiency virus, Alzheimer’s disease, Parkinson’s disease, and other neurodegenerative diseases. However, there are relatively few studies on the structure–activity relationship (SAR) of tobacco cembranoid diterpenes. Therefore, future studies should focus on their structural modification, SAR and biogenic relationships.

Styles APA, Harvard, Vancouver, ISO, etc.

15

HWU, J. R., et J. M. WETZEL. « ChemInform Abstract : Silicon-Promoted Ring Contractions in the Formation of Carbocyclic Spiro Compounds. Total Synthesis of (-)-Solavetivone. » ChemInform 23, n^o 26 (21 août 2010) : no. http://dx.doi.org/10.1002/chin.199226254.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

16

Schmiedel, Volker Martin, et Hans-Ulrich Reissig. « Alkoxyallenes as Starting Materials for the Syntheses of Natural Products ». Current Organic Chemistry 23, n^o 27 (15 janvier 2020) : 2976–3003. http://dx.doi.org/10.2174/1385272824666191218115731.

Texte intégral

Résumé :

Alkoxyallenes are easily available and versatile building blocks for the preparation of a variety of natural products (terpenes, polyketides, alkaloids, amino acids, carbohydrates etc.) originating from different classes. The synthetic use of the three allene carbon atoms frequently follows the “normal” reactivity pattern showing that alkoxyallenes can be regarded as special enol ethers. Additions of alcohols or amines to alkoxyallenes form vinyl-substituted O,O- or N,O-acetals that are frequently used in ring-closing metathesis reactions. This methodology delivers crucial heterocyclic units of the target compounds. Enantioselective additions provide products with high enantiopurity. Alternatively, an “Umpolung” of reactivity of alkoxyallenes is achieved by lithiation at C-1 and subsequent reaction with electrophiles, such as alkyl halides, carbonyl compounds, imines or nitrones. High stereoselectivity of the addition step can be achieved by substrate control or auxiliary control. The high diastereo- or enantioselectivity is transferred to the subsequent acyclic or cyclic products. The cyclization of primary addition products occurs efficiently under mild conditions and provides functionalized dihydrofuran, dihydropyrrole or 1,2-oxazine derivatives. These are valuable intermediates for the synthesis of a variety of heterocyclic natural products. Nazarov cyclizations or gold catalyzed rearrangements allow the synthesis of five- and six-membered carbocyclic compounds that are also used for natural product synthesis. Dedicated to Dr. Reinhold Zimmer, a pioneer of alkoxyallene chemistry, on the occasion of his 60th birthday.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Zaki, Magdi E. A., Sami A. Al-Hussain, Aamal A. Al-Mutairi, Vijay H. Masand, Abdul Samad et Rahul D. Jawarkar. « Mechanistic Analysis of Chemically Diverse Bromodomain-4 Inhibitors Using Balanced QSAR Analysis and Supported by X-ray Resolved Crystal Structures ». Pharmaceuticals 15, n^o 6 (14 juin 2022) : 745. http://dx.doi.org/10.3390/ph15060745.

Texte intégral

Résumé :

Bromodomain-4 (BRD-4) is a key enzyme in post-translational modifications, transcriptional activation, and many other cellular processes. Its inhibitors find their therapeutic usage in cancer, acute heart failure, and inflammation to name a few. In the present study, a dataset of 980 molecules with a significant diversity of structural scaffolds and composition was selected to develop a balanced QSAR model possessing high predictive capability and mechanistic interpretation. The model was built as per the OECD (Organisation for Economic Co-operation and Development) guidelines and fulfills the endorsed threshold values for different validation parameters (R2tr = 0.76, Q2LMO = 0.76, and R2ex = 0.76). The present QSAR analysis identified that anti-BRD-4 activity is associated with structural characters such as the presence of saturated carbocyclic rings, the occurrence of carbon atoms near the center of mass of a molecule, and a specific combination of planer or aromatic nitrogen with ring carbon, donor, and acceptor atoms. The outcomes of the present analysis are also supported by X-ray-resolved crystal structures of compounds with BRD-4. Thus, the QSAR model effectively captured salient as well as unreported hidden pharmacophoric features. Therefore, the present study successfully identified valuable novel pharmacophoric features, which could be beneficial for the future optimization of lead/hit compounds for anti-BRD-4 activity.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Girisha, Marisiddaiah, Hemmige S. Yathirajan, Jerry P. Jasinski et Christopher Glidewell. « Different acid–base behaviour of a pyrazole and an isoxazole with organic acids : crystal and molecular structures of the salt 3-(4-fluorophenyl)-1H-pyrazolium 2,4,6-trinitrophenolate and of the cocrystal 4-amino-N-(3,4-dimethyl-1,2-oxazol-5-yl)benzenesulfonamide–3,5-dinitrobenzoic acid (1/1) ». Acta Crystallographica Section C Structural Chemistry 72, n^o 8 (12 juillet 2016) : 612–18. http://dx.doi.org/10.1107/s2053229616010494.

Texte intégral

Résumé :

Pyrazole and isoxazole rings differ only in the notional replacement of a potential hydrogen-bond-donor NH unit in pyrazole by a potential hydrogen-bond-acceptor O atom in isoxazole. It is thus of interest to compare the hydrogen-bonding characteristics of these rings. (4-Fluorophenyl)pyrazole undergoes protonation in the presence of 2,4,6-trinitrophenol to yield the salt 3-(4-fluorophenyl)-1H-pyrazolium 2,4,6-trinitrophenolate, C9H8FN2+·C6H2N3O7−, (I), whereas there is no proton transfer between 4-amino-N-(3,4-dimethyl-1,2-oxazol-5-yl)benzenesulfonamide and 3,5-dinitrobenzoic acid, whose reaction gives the 1:1 cocrystal, C11H13N3O3S·C7H4N2O6, (II). The bond lengths in salt (I) provide evidence for aromatic-type delocalization in the pyrazolium ring and for extensive delocalization of the negative charge into the ring of the trinitrophenolate anion. The O atoms of one of the nitro groups in the trinitrophenolate anion are disordered over two sets of atomic sites having occupancies of 0.571 (6) and 0.429 (6), but all of the other substituents on the carbocyclic rings are fully ordered. The ions in salt (I) are linked by an extensive series of N—H...O hydrogen bonds to form a three-dimensional framework structure, and in cocrystal (II), the molecular components are linked by a combination of O—H...N and N—H...O hydrogen bonds to form complex bilayers. Comparisons are made with some related compounds.

Styles APA, Harvard, Vancouver, ISO, etc.

19

Wojtasik, Katarzyna, Monika Pokladko-Kowar et Ewa Gondek. « Optimization of Bulk Heterojunction Photovoltaic Structures with Heterocyclic Derivatives ». Crystals 13, n^o 5 (27 avril 2023) : 734. http://dx.doi.org/10.3390/cryst13050734.

Texte intégral

Résumé :

Photovoltaic structures of the bulk heterojunction type were fabricated, in which derivatives of N,N-diethylamine-3-Methyl-1-Phenyl-1H-pyrazolo[3,4-b]quinoxalines were used as the active layer. The compounds differed in the position of the electron-donating substituent in the carbocyclic ring. Four isomers were subjected to UV-Vis spectrophotometric measurements in solvents of different polarities. The absorption characteristics were experimentally determined for the tested derivatives. The values of HOMO-LUMO levels were determined by means of quantum chemical calculations using the HyperChem software. The current–voltage and dispersion characteristics of the produced OPV were determined. The spectral characteristics of the refractive indices and extinction coefficients of the active layers were determined using the spectroscopic ellipsometry method. These results were used in the analysis and optimization of photovoltaic structures. It was shown that the location of the N,N-diethylamine substituent affects the photophysical properties of the structure and the photovoltaic properties. The optimization of the OPV_2 photovoltaic structure using the coherent model and the 2 × 2 matrix method can be successfully used in modeling optical multilayer structures, including photovoltaic structures.

Styles APA, Harvard, Vancouver, ISO, etc.

20

Kudrevich, Svetlana V., Johan E. Van Lier, Maria G. Galpern et Evgeny A. Luk'yanets. « Substituted tetra-2,3-pyrazinoporphyrazines. Part I. Angular annelation of tetra-2,3-quinoxalinoporphyrazine ». Canadian Journal of Chemistry 74, n^o 4 (1 avril 1996) : 508–15. http://dx.doi.org/10.1139/v96-055.

Texte intégral

Résumé :

Several derivatives of 2,3-dicyanopyrazine were prepared via the condensation of o-quinones with diaminomaleodinitrile. Benzo[f]quinoxaline-2,3-dinitrile was obtained from 1,2-naphthoquinone, and a series of isomeric, di-tert-butyl substituted 5,6-(9,10-phenanthro)-2,3-dicyanopyrazines were prepared from the corresponding di-tert-butyl-9,10-phenanthrenequinones. Complexation of benzo[f]quinoxaline-2,3-dinitrile, and unsubstituted 5,6-(9,10-phenanthro)-2,3-dicyanopyrazine, with an appropriate metal salt yielded metal complexes of tetra-2,3-(benzo[f]quinoxalino)porphyrazine and tetra-2,3-[5,6-(9,10-phenanthro)]porphyrazine, respectively. Metal-free tetra-2,3-[5,6-(9,10-phenanthro)porphyrazine was obtained from the dilithium derivative by demetallation in HCl. These compounds have limited solubility in organic solvents, such as quinoline, and are aggregated in solutions. To eliminate the aggregation phenomenon and to determine the spectral properties of angularly annelated naphthalocyanine aza analogs, we prepared several isomeric tetra-2,3-[5,6-(di-tert-butyl-9,10-phenanthro)pyrazino]porphyrazines. These octa(tert-butyl) substituted complexes were synthesized via complexation of di-tert-butyl substituted 5,6-(9,10-phenanthro)-2,3-dicyanopyrazines with metal salts in the presence of urea, quinoline, and tri(n-butyl)amine, and purified by silica gel chromatography. They are soluble in chloroform and substantially monomerized in solutions. A hypsochromic shift of the Q-band of octaaza naphthalocyanines versus their carbocyclic analogs was observed for all aza analogs, with the extent of the shift depending on the composition of the aromatic macrocycle. Thus, the first angularly annelated benzo ring addition causes a hypsochromic shift (∼25 nm) of the Q-band of tetra-2,3-quinoxalinoporphyrazine, whereas addition of a second condensed benzo ring has little effect. Key words: phthalocyanine, aza analog, tetra-2,3-quinoxalinoporphyrazine, angular annelation.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Chen, Xuefei, Min Xu, Jin Lü, Jianguo Xu, Yemin Wang, Shuangjun Lin, Zixin Deng et Meifeng Tao. « Biosynthesis of Tropolones inStreptomycesspp. : Interweaving Biosynthesis and Degradation of Phenylacetic Acid and Hydroxylations on the Tropone Ring ». Applied and Environmental Microbiology 84, n^o 12 (13 avril 2018) : e00349-18. http://dx.doi.org/10.1128/aem.00349-18.

Texte intégral

Résumé :

ABSTRACTTropolonoids are important natural products that contain a unique seven-membered aromatic tropolone core and exhibit remarkable biological activities. 3,7-Dihydroxytropolone (DHT) isolated fromStreptomycesspecies is a multiply hydroxylated tropolone exhibiting antimicrobial, anticancer, and antiviral activities. In this study, we determined the DHT biosynthetic pathway by heterologous expression, gene deletion, and biotransformation. Ninetrlgenes and some of the aerobic phenylacetic acid degradation pathway genes (paa) located outside thetrlbiosynthetic gene cluster are required for the heterologous production of DHT. ThetrlAgene encodes a single-domain protein homologous to the C-terminal enoyl coenzyme A (enoyl-CoA) hydratase domain of PaaZ. TrlA truncates the phenylacetic acid catabolic pathway and redirects it toward the formation of heptacyclic intermediates. TrlB is a 3-deoxy-d-arabino-heptulosonic acid-7-phosphate (DAHP) synthase homolog. TrlH is an unusual bifunctional protein bearing an N-terminal prephenate dehydratase domain and a C-terminal chorismate mutase domain. TrlB and TrlH enhancedde novobiosynthesis of phenylpyruvate, thereby providing abundant precursor for the prolific production of DHT inStreptomycesspp. Six seven-membered carbocyclic compounds were identified from thetrlC,trlD,trlE, andtrlFdeletion mutants. Four of these chemicals, including 1,4,6-cycloheptatriene-1-carboxylic acid, tropone, tropolone, and 7-hydroxytropolone, were verified as key biosynthetic intermediates. TrlF is required for the conversion of 1,4,6-cycloheptatriene-1-carboxylic acid into tropone. The monooxygenases TrlE and TrlCD catalyze the regioselective hydroxylations of tropone to produce DHT. This study reveals a natural association of anabolism of chorismate and phenylpyruvate, catabolism of phenylacetic acid, and biosynthesis of tropolones inStreptomycesspp.IMPORTANCETropolonoids are promising drug lead compounds because of the versatile bioactivities attributed to their highly oxidized seven-membered aromatic ring scaffolds. Our present study provides clear insight into the biosynthesis of 3,7-dihydroxytropolone (DHT) through the identification of key genes responsible for the formation and modification of the seven-membered aromatic core. We also reveal the intrinsic mechanism of elevated production of DHT and related tropolonoids inStreptomycesspp. The study on DHT biosynthesis inStreptomycesexhibits a good example of antibiotic production in which both anabolic and catabolic pathways of primary metabolism are interwoven into the biosynthesis of secondary metabolites. Furthermore, our study sets the stage for metabolic engineering of the biosynthetic pathway for natural tropolonoid products and provides alternative synthetic biology tools for engineering novel tropolonoids.

Styles APA, Harvard, Vancouver, ISO, etc.

22

Aksenov, A. V., N. A. Aksenov, A. S. Lyakhovnenko, A. B. Kumshaeva et I. V. Aksenova. « Novel three-component reaction of perimidines with 1,3,5-triazines and carbonyl compounds in polyphosphoric acid. an efficient method for peri-annelation of a carbocyclic and pyridine ring ». Chemistry of Heterocyclic Compounds 48, n^o 4 (juillet 2012) : 634–41. http://dx.doi.org/10.1007/s10593-012-1037-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

23

Aksenov, A. V., N. A. Aksenov, A. S. Lyakhovnenko, A. B. Kumshaeva et I. V. Aksenova. « ChemInform Abstract : Novel Three-Component Reaction of Perimidines with 1,3,5-Triazines and Carbonyl Compounds in Polyphosphoric Acid. An Efficient Method for peri-Anellation of a Carbocyclic and Pyridine Ring. » ChemInform 43, n^o 50 (29 novembre 2012) : no. http://dx.doi.org/10.1002/chin.201250165.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

24

Girisha, Marisiddaiah, Belakavadi K. Sagar, Hemmige S. Yathirajan, Ravindranath S. Rathore, Manpreet Kaur, Jerry P. Jasinski et Christopher Glidewell. « Eight Schiff bases derived from various salicylaldehydes : phenol–imine and keto–amine forms, conformational disorder, and supramolecular assembly in one and two dimensions ». Acta Crystallographica Section C Structural Chemistry 74, n^o 10 (7 septembre 2018) : 1094–104. http://dx.doi.org/10.1107/s2053229618012287.

Texte intégral

Résumé :

Structures are reported for eight Schiff bases derived from various salicylaldehydes: five are newly synthesized and re-investigations are reported for three previously reported structures, leading, in each case, to some revision of previous conclusions. In (E)-N-(3,4-dimethylisoxazol-5-yl)-4-[(2-hydroxybenzylidene)amino]benzenesulfonamide, C18H17N3O4S, (I), and (E)-4-[(5-bromo-2-hydroxy-3-methoxybenzylidene)amino]-N-(3,4-dimethylisoxazol-5-yl)benzenesulfonamide. C19H18BrN3O5S, (II), the isoxazole rings adopt different orientations relative to the rest of the molecules, despite the additional substituents in (II) being in the aryl ring remote from the isoxazole unit. The molecules of both (E)-4-bromo-2-[(2-hydroxyphenylimino)methyl]-6-methoxyphenol, C14H12BrNO3, (III), and (E)-4-bromo-2-methoxy-6-[(2-methoxyphenylimino)methyl]phenol, C15H14BrNO3, (IV), are both effectively planar; while (III) adopts the phenol–imine constitution, (IV) adopts the keto–amine constitution. (E)-2-Methoxy-6-[(2-methoxyphenylimino)methyl]phenol, C15H15NO3, (V), which was determined previously using powder X-ray data assuming the phenol–imine constitution, has now been refined from single-crystal X-ray data, confirming the phenol–imine constitution. In (E)-3-benzoyl-2-[(5-fluoro-2-hydroxybenzylidene)amino]-4,5,6,7-tetrahydrobenzo[b]thiophene, C22H18FNO2S, (VI), the fused carbocyclic ring exhibits conformational disorder; both disorder components, having populations of 0.705 (4) and 0.295 (4), adopt half-chair conformations. The isostructural (E)-3-benzoyl-2-[(2-hydroxybenzylidene)amino)]-4,5,6,7-tetrahydrobenzo[b]thiophene, C22H19NO2S, (VII), which was originally reported as having a fully ordered structure [Kauret al.(2014).Acta Cryst.E70, o476–o477], has been rerefined using the original data set and found to exhibit the same type of disorder as found in (VI), with disordered populations having occupancies of 0.851 (3) and 0.149 (3). The triclinic polymorph of (E)-[(2-hydroxyphenylimino)methyl]phenol, C13H11NO2, (VIII), which crystallizes withZ′ = 2 in the space groupP-1, has been described variously as occurring as the keto–amine tautomer [Maciejewskaet al.(1999).J. Phys. Org. Chem.12, 875–880] and as the phenol–imine tautomer [Tunçet al.(2009).J. Chem. Crystallogr.39, 672–676]. Rerefinement of this structure using one of the original data sets shows that both of the independent molecules exist in the keto–amine form. In the structures of compounds (I), (VI), (VII) and (VIII), hydrogen bonds generate simple chains, while a chain of rings is formed in (V). Sheets are formed by hydrogen bonds in both (II) and (III), while in (IV), the sheet structure is built from aromatic π–π stacking interactions.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Dragutan, V., I. Dragutan et A. T. Balaban. « Metathesis Catalysed by the Platinum Group Metals ». Platinum Metals Review 44, n^o 4 (1 octobre 2000) : 168–72. http://dx.doi.org/10.1595/003214000x444168172.

Texte intégral

Résumé :

The first two parts of this paper appeared in the April and July issues of this Journal. Part I looked at types of platinum group metals catalysts and metathesis activity and selectivity. Part II examined specific syntheses catalysed by these catalysts, in particular, reactions catalysed by ruthenium carbenes. This resulted in the syntheses of various carbocycles, heterocycles, metallacycles, crown ethers, polycyclic polymers, natural compounds and sub-units of biologically active compounds. The concluding part of this review deals first with acyclic diene metathesis and then with ring-opening metathesis polymerisations, and ranges of products formed by these reactions are given.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Bolton, R., et M. H. Sosabowski. « ChemInform Abstract : Polycyclic Compounds Comprising a Pyridine and Two or More Carbocyclic Rings ». ChemInform 30, n^o 44 (13 juin 2010) : no. http://dx.doi.org/10.1002/chin.199944322.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

27

Okumura, Mikiko, et David Sarlah. « Arenophile-Mediated Photochemical Dearomatization of Nonactivated Arenes ». CHIMIA International Journal for Chemistry 74, n^o 7 (12 août 2020) : 577–83. http://dx.doi.org/10.2533/chimia.2020.577.

Texte intégral

Résumé :

Aromatic compounds are one of the most abundant classes of organic molecules and find utility as precursors for alicyclic hydrocarbon building blocks. While many established dearomatization reactions are exceptionally powerful, dearomatization with concurrent introduction of functionality, i.e. dearomative functionalization, is still a largely underdeveloped field. This review aims to provide an overview of our recent efforts and progress in the development of dearomative functionalization of simple and nonactivated arenes using arenophile-arene cycloaddition platform. These cycloadducts, formed via a visible-light-mediated [4+2]-photocycloaddition, can be elaborated in situ through olefin chemistry or transition-metal-catalyzed ring-opening with carbon-, nitrogen-, and oxygen-based nucleophiles, providing access to diverse structures with functional and stereochemical complexity. Moreover, the dearomatized products are amenable to further elaborations, which effectively install other functionalities onto the resulting alicyclic carbocycles. The utility of the arenophile-mediated dearomatization methods are also highlighted by the facile syntheses of natural products and bioactive compounds through novel disconnections.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Zhaocui, Xudong, Hanqiao, Xinyi, Guoxu et Leiling. « Five New Meroterpenoids from the Fruiting Bodies of the Basidiomycete Clitocybe clavipes with Cytotoxic Activity ». Molecules 24, n^o 22 (6 novembre 2019) : 4015. http://dx.doi.org/10.3390/molecules24224015.

Texte intégral

Résumé :

Five new meroterpenoids, clavipols A–B (1–2) with a 12-membered ether ring and clavilactones G–I (3–5) having a 10-membered carbocycle connected to a hydroquinone and an α,β-epoxy/unsaturated lactone, were obtained from the fruiting bodies of the basidiomycete Clitocybe clavipes. Their structures were determined by comprehensive analysis of their spectroscopic data, and the absolute configuration of 1 was established by quantum chemical calculations of electronic circular dichroism (ECD). All the isolated compounds (1–5) were tested for their cytotoxic activity against three human tumor cell lines (Hela, SGC-7901, and SHG-44) in vitro after treatment for 48 h. Compound 4 exhibited moderate cytotoxic activity against Hela and SGC-7901 tumor cell lines, with IC50 values of 23.5 and 14.5 µM, respectively.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Masdeu, Carme, Maria Fuertes, Endika Martin-Encinas, Asier Selas, Gloria Rubiales, Francisco Palacios et Concepcion Alonso. « Fused 1,5-Naphthyridines : Synthetic Tools and Applications ». Molecules 25, n^o 15 (31 juillet 2020) : 3508. http://dx.doi.org/10.3390/molecules25153508.

Texte intégral

Résumé :

Heterocyclic nitrogen compounds, including fused 1,5-naphthyridines, have versatile applications in the fields of synthetic organic chemistry and play an important role in the field of medicinal chemistry, as many of them have a wide range of biological activities. In this review, a wide range of synthetic protocols for the construction of this scaffold are presented. For example, Friedländer, Skraup, Semmlere-Wolff, and hetero-Diels-Alder, among others, are well known classical synthetic protocols used for the construction of the main 1,5-naphthyridine scaffold. These syntheses are classified according to the nature of the cycle fused to the 1,5-naphthyridine ring: carbocycles, nitrogen heterocycles, oxygen heterocycles, and sulphur heterocycles. In addition, taking into account the aforementioned versatility of these heterocycles, their reactivity is presented as well as their use as a ligand for metal complexes formation. Finally, those fused 1,5-naphthyridines that present biological activity and optical applications, among others, are indicated.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Ortuño, Rosa M. « Carbocycle-Based Organogelators : Influence of Chirality and Structural Features on Their Supramolecular Arrangements and Properties ». Gels 7, n^o 2 (1 mai 2021) : 54. http://dx.doi.org/10.3390/gels7020054.

Texte intégral

Résumé :

The rational design and engineer of organogel-based smart materials and stimuli-responsive materials with tuned properties requires the control of the non-covalent forces driving the hierarchical self-assembly. Chirality, as well as cis/trans relative configuration, also plays a crucial role promoting the morphology and characteristics of the aggregates. Cycloalkane derivatives can provide chiral chemical platforms allowing the incorporation of functional groups and hydrophobic structural units able for a convenient molecular stacking leading to gels. Restriction of the conformational freedom imposed by the ring strain is also a contributing issue that can be modulated by the inclusion of flexible segments. In addition, donor/acceptor moieties can also be incorporated favoring the interactions with light or with charged species. This review offers a perspective on the abilities and properties of carbocycle-based organogelators starting from simple cycloalkane derivatives, which were the key to establish the basis for an effective self-assembling, to sophisticated polycyclic compounds with manifold properties and applications.

Styles APA, Harvard, Vancouver, ISO, etc.

31

Yuan, Chengye, et Chaozhong Li. « STUDIES ON ORGANOPHOSPHORUS COMPOUNDS 90. STEREOSELECTIVE SYNTHESIS OF FUSED CARBOCYCLIC AND ISOXAZOLINE RINGS VIA INTRAMOLECULAR SILYL NITRONATE-OLEFIN CYCLOADDITIONS ». Phosphorus, Sulfur, and Silicon and the Related Elements 103, n^o 1-4 (juin 1995) : 133–35. http://dx.doi.org/10.1080/10426509508027372.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

32

Schaper, Wiebke, Ilona Lange, Dagmar Henschel, Oliver Moers, Armand Blaschette et Peter G. Jones. « Polysulfonylamine, CXL [1]. N-Cycloalkyldimesylamine C„H2n-1/N(SO2CH3)2 : Synthesen (n = 3 -6 ), Festkörper-Molekülstrukturen (n = 4 -6 ) Und Rolle Schwacher Wasserstoffbrücken C-H···O In Den Kristallstrukturen ». Zeitschrift für Naturforschung B 56, n^o 8 (1 août 2001) : 765–77. http://dx.doi.org/10.1515/znb-2001-0810.

Texte intégral

Résumé :

The new disulfonylamines R -N (SO2Me)2, where R = cyclopropyl (1), cyclobutyl (2), cyclopentyl (3) or cyclohexyl (4), were prepared according to an established one-step procedure (condensation of RNH2 with two equivalents of MeSO2Cl, NaH as basic auxiliary). Whereas the structure determination for 1 was marred by severe disorder, compounds 2 -4 have been characterized by low-temperature X-ray diffraction (2: monoclinic, space group P21 Z ' = 2, pseudo-P21/c packing; 3: triclinic, P1̄, Z' - 1; 4: orthorhombic, Pbca, Z ' = 1). The four independent molecules display puckered carbocycles, whereby the electronegative (MeSO2)2N substituent occupies an equatorial position, leading to short intramolecular C - H···O contacts (2: angles of ring pucker φ ≈ 30-33°; 3: envelope conformation, φ ≈ 40°; 4: chair conformation, φ1 ≈ φ2 51°). In accordance with known congener structures, the C(sp3)-N (S)2 moieties feature trigonal-planar N configurations and unusually long C -N bonds (ranges for 2-4: C -N 148.8-150.8 pm, S -N 166.6-168.9 pm, S -N -S 118.3-119.3°). The three crystal packings are governed by a plethora of weak intermolecular hydrogen bonds C(sp3)-H···O , and a thorough survey of these interactions reveals that the inductively activated methyl groups are distinctly more efficient hydrogen bond donors than the methine and methylene ring groups. In each structure, the principal hydrogen bonds create layer substructures parallel to a unit cell face, which are cross-linked by the remaining C -H···O contacts to form three-dimensional networks

Styles APA, Harvard, Vancouver, ISO, etc.

33

Yuan, Chengye, et Chaozhong Li. « Studies on organophosphorus compounds 80. Stereoselective synthesis of fused carbocyclic and isoxazoline rings via intramolecular cycloaddition of nitrile oxides derived from α-nitroalkenes ». Tetrahedron Letters 34, n^o 37 (septembre 1993) : 5959–62. http://dx.doi.org/10.1016/s0040-4039(00)73826-3.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

34

YUAN, C., et C. LI. « ChemInform Abstract : Studies on Organo-Phosphorus Compounds. Part 80. Stereoselective Synthesis of Fused Carbocyclic and Isoxazoline Rings via Intramolecular Cycloaddition of Nitrile Oxides Derived from α-Nitroalkenes. » ChemInform 25, n^o 4 (19 août 2010) : no. http://dx.doi.org/10.1002/chin.199404207.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Singha, Tushar, Ganesh Arjun Kadam et Durga Prasad Hari. « Photocatalyzed redox-neutral decarboxylative Dowd-Beckwith radical-polar crossover reaction : an efficient approach to functionalized medium-sized carbocyclic compounds ». Chemical Science, 2023. http://dx.doi.org/10.1039/d3sc01908j.

Texte intégral

Résumé :

The Dowd-Beckwith reaction, a ring-expansion of carbonyl compounds via alkoxy radicals, is a powerful approach for synthesizing medium to large-sized carbocyclic scaffolds, which takes benefit of existing ring structures and...

Styles APA, Harvard, Vancouver, ISO, etc.

36

Pal, Shantanu, Girish Chandra, Samir Kumar Mondal et Birkishore Mahto. « Current Strategies on the Enantioselective Synthesis of Modified Nucleosides ». Synlett, 16 novembre 2023. http://dx.doi.org/10.1055/a-2212-8502.

Texte intégral

Résumé :

After the isolation of two carbocyclic nucleosides, viz Neplanocin A and Aristeromycin, from natural sources, a revolution came into the scientific community to develop more versatile, therapeutically useful compounds. For this purpose, many new methods for the synthesis of the carbocyclic framework of nucleosides have been developed. The consequences of this effort led to the successful development of many marketable drugs. Due to the inherent benefits such as higher lipophilicity and metabolic stability associated with carbocyclic nucleosides, like resistance against glycosidic hydrolysis and modification of aromatic bases by cellular phosphorylases, make them popular for the development of drugs against cancer and different viruses. Classically, carbocyclic nucleosides of various ring sizes and configurations have been synthesized starting from a chiral pool such as ribose and glucose, etc., but recently, many other new asymmetric versions have also been developed. Herein, we present a recent development in the catalytic enantioselective synthesis of nucleoside analogues, including carbocyclic and other varieties. This review provides new insights into the future development of modified nucleosides.

Styles APA, Harvard, Vancouver, ISO, etc.

37

Fikatas, Antonios, Peter Vervaeke, Eef Meyen, Nuria Llor, Sergi Ordeix, Ine Boonen, Magda Bletsa et al. « A Novel Series of Indole Alkaloid Derivatives Inhibit Dengue and Zika Virus Infection by Interference with the Viral Replication Complex ». Antimicrobial Agents and Chemotherapy 65, n^o 8 (16 juillet 2021). http://dx.doi.org/10.1128/aac.02349-20.

Texte intégral

Résumé :

Here, we identified a novel class of compounds which demonstrated good antiviral activity against dengue and Zika virus infection. These derivatives constitute intermediates in the synthesis of indole (ervatamine-silicine) alkaloids and share a tetracyclic structure, with an indole and a piperidine fused to a seven-membered carbocyclic ring.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Jansa, Petr, Ivana Císařová et Eliška Matoušová. « Oxidative Cleavage and Ring Reconstruction in the Synthesis of Amaryllidaceae Alkaloid Analogues ». European Journal of Organic Chemistry, 29 novembre 2023. http://dx.doi.org/10.1002/ejoc.202301021.

Texte intégral

Résumé :

This study presents the synthesis of analogues of bioactive Amaryllidaceae alkaloids that contain a five‐membered ring C and a quaternary carbon centre. The synthesis was carried out in a divergent manner, starting from a common intermediate, keto aldehyde 1a. This intermediate was obtained by oxidative cleavage of a carbocyclic ring present in the previously synthesised tetracyclic compounds. Subsequent closure of a new heterocyclic ring B using different methods led to products with structural cores found in naturally occuring alkaloids such as pretazettine, tazettine or macronine. In addition, an analogue of egonine was prepared from the same intermediate. Our approach thus provides access to multiple structural types of potentially bioactive molecules.

Styles APA, Harvard, Vancouver, ISO, etc.

39

Bao, Ming, et Michael P. Doyle. « Asymmetric [3+n]‐cycloaddition reactions of donor‐acceptor cyclopropanes ». ChemCatChem, 17 octobre 2023. http://dx.doi.org/10.1002/cctc.202301090.

Texte intégral

Résumé :

[3+n]‐Cycloaddition reactions that employ donor‐acceptor cyclopropanes using either chiral catalysts and racemic cyclopropanes or achiral catalysts and chiral, non‐racemic, cyclopropanes have become useful transformations for the construction of carbocyclic and heterocyclic compounds, with both processes offering mechanistic and structural advantages in ring formation. Although the vast majority of asymmetric cycloaddition reactions of donor‐acceptor cyclopropanes have been performed with racemic cyclopropane compounds catalyzed by Lewis acids with chiral ligands, optically active cyclopropane compounds can serve the same role using Lewis acids without chiral ligands. This review covers the use of chiral catalysts with racemic donor‐acceptor cyclopropanes and the use of chiral non‐racemic donor‐acceptor cyclopropanes with achiral Lewis acid catalysts.

Styles APA, Harvard, Vancouver, ISO, etc.

40

Zhao, Dong-Lin, Lu-Jia Yang, Ting Shi, Chao-Yi Wang, Chang-Lun Shao et Chang-Yun Wang. « Potent Phytotoxic Harziane Diterpenes from a Soft Coral-Derived Strain of the Fungus Trichoderma harzianum XS-20090075 ». Scientific Reports 9, n^o 1 (16 septembre 2019). http://dx.doi.org/10.1038/s41598-019-49778-7.

Texte intégral

Résumé :

Abstract Two new harziane diterpene lactones, possessing a 6/5/7/5-fused carbocyclic core containing a lactone ring system, harzianelactones A and B (1 and 2), and five new harziane diterpenes, harzianones A–D (3–6) and harziane (7), were isolated from the soft coral-derived fungus Trichoderma harzianum XS-20090075. Their structures were determined by extensive NMR spectroscopic data, ECD and OR calculations, as well as X-ray diffraction. The isolated compounds exhibited potent phytotoxicity against seedling growth of amaranth and lettuce. Harziane diterpenes were rarely reported for their remarkably bioactivities, and it was the first report to study the phytotoxicity of harziane diterpenes, which provide a new application of such compounds in agriculture for future research.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Jankowiak, Aleksandra, Piotr Kaszynski, William R. Tilford, Kiminori Ohta, Adam Januszko, Takashi Nagamine et Yasuyuki Endo. « Ring-alkyl connecting group effect on mesogenic properties of p-carborane derivatives and their hydrocarbon analogues ». Beilstein Journal of Organic Chemistry 5 (30 décembre 2009). http://dx.doi.org/10.3762/bjoc.5.83.

Texte intégral

Résumé :

The effect of the phenyl–alkyl connecting group on mesogenic properties of several series of isostructural compounds containing p-carborane (A and B), bicyclo[2.2.2]octane (C), and benzene (D) was investigated using thermal and optical methods. Results demonstrated that mesophase stability in the series containing A–D follows the order (Alk)CH2CH2– < (Alk)OOC– < (Alk)CH2O– < (Alk)COO–. Surprisingly, the connecting groups (Alk)CH2CH2– and (Alk)OOC– destabilize the mesophase significantly stronger for carboranes (A and B) than for carbocyclic derivatives (C and D). Analysis indicates that this effect may have quadrupolar and conformational origin.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Takahashi, Hidetoshi, Kazuhiro Yoshida et Akira Yanagisawa. « ChemInform Abstract : Synthesis of Carbocyclic Aromatic Compounds Using Ruthenium-Catalyzed Ring-Closing Enyne Metathesis. » ChemInform 40, n^o 39 (29 septembre 2009). http://dx.doi.org/10.1002/chin.200939041.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

43

Babar, Kashaf, Ameer Fawad Zahoor, Sajjad Ahmad et Rabia Akhtar. « Recent synthetic strategies toward the synthesis of spirocyclic compounds comprising six-membered carbocyclic/heterocyclic ring systems ». Molecular Diversity, 21 juillet 2020. http://dx.doi.org/10.1007/s11030-020-10126-x.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

44

Sinnwell, Michael A., Ryan H. Groeneman, Benjamin J. Ingenthron, Changan Li et Leonard R. MacGillivray. « Supramolecular construction of a cyclobutane ring system with four different substituents in the solid state ». Communications Chemistry 4, n^o 1 (10 mai 2021). http://dx.doi.org/10.1038/s42004-021-00493-3.

Texte intégral

Résumé :

AbstractMethods to form cyclobutane rings by an intermolecular [2 + 2] cross-photoreaction (CPR) with four different substituents are rare. These reactions are typically performed in the liquid phase, involve multiple steps, and generate product mixtures. Here, we report a CPR that generates a cyclobutane ring with four different aryl substituents. The CPR occurs quantitatively, without side products, and without a need for product purification. Generally, we demonstrate how face-to-face stacking interactions of aromatic rings can be exploited in the process of cocrystallization and the field of crystal engineering to stack and align unsymmetrical alkenes in CPRs to afford chiral cyclobutanes with up to four different aryl groups via binary cocrystals. Overall, we expect the process herein to be useful to generate chiral carbon scaffolds, which is important given the presence of four-membered carbocyclic rings as structural units in biological compounds and materials science.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Kumar, K. Shiva, Kishan Gugulothu, Sabbasani Rajasekhara Reddy et Katta Venkateswarlu. « A Critical Review on Recent Advances in Base-Assisted Smiles Rearrangement ». Current Organic Chemistry 26 (9 mai 2022). http://dx.doi.org/10.2174/1385272826666220509143140.

Texte intégral

Résumé :

Abstract: Rearrangement reactions of organic substrates is a versatile and sustainable tool in the construction of complex and bioactive organics by virtue of their atom-economic, step-economic and waste-, time- as well as energy-minimizing attributes. The X → C (or Y) aryl rearrangement reaction through an intramolecular nucleophilic aromatic substitution is referred to as Smiles rearrangement. The Smiles rearrangement enables access to complex natural products and is a useful tool to obtain various types of compounds with diversified applications which have undergone a potent revival in recent years. In this review we summarize the recent reports on Smiles rearrangement and almost of them require a base. A few examples of the reported base-free Smiles rearrangements were also reviewed to provide comprehensive information on the selected topic. The literature review covers the published work on Smiles rearrangement reaction since 2017. The published work in these articles include simple Smiles, Truce-Smiles, radical Smiles, Ugi-Smiles, light-assisted Smiles, Dohmori-Smiles, electrochemical Smiles and phospha-Smiles rearrangement reactions for the construction of a variety of organic compounds including acyclic, heterocyclic, carbocyclic and polycyclic compounds. The formation of organic compounds with unusual ring sizes has also been discussed in the published work. Several domono/sequential reactions were also observed in these reports involving Smiles rearrangement as crucial step. The selected examples demonstrate the synthetic power of this approach and hence this review may be highly useful to the synthetic chemists aimed to use Smiles rearrangement in their plan.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Chawla, Pooja A., Parul Grover, Lovekesh Mehta, Anjleena Malhotra, Garima Kapoor, Kandasamy Nagarajan, Parvin Kumar et Viney Chawla. « Exploring the multitarget potential of iridoids : Advances and Applications ». Current Topics in Medicinal Chemistry 23 (22 décembre 2022). http://dx.doi.org/10.2174/1568026623666221222142217.

Texte intégral

Résumé :

Abstract: Iridoids are secondary plant metabolites that are multitarget compounds active against various diseases. Iridoids are structurally classified into iridoid glycosides and non-glycosidic iridoids according to the presence or absence of intramolecular glycosidic bonds; additionally, iridoid glycosides can be further subdivided into carbocyclic iridoids and secoiridoids. These monoterpenoids belong to the cyclopentan[c]-pyran system, which has a wide range of biological activities, including antiviral, anticancer, antiplasmodial, neuroprotective, anti-thrombolytic, antitrypanosomal, antidiabetic, hepatoprotective, anti-oxidant, antihyperlipidemic and anti-inflammatory properties. The basic chemical structure of iridoids in plants (the iridoid ring scaffold) is biosynthesized in plants by the enzyme iridoid synthase using 8-oxogeranial as a substrate. With advances in phytochemical research, many iridoid compounds with novel structure and outstanding activity have been identified in recent years. Biologically active iridoid derivatives have been found in a variety of plant families, including Plantaginaceae, Rubiaceae, Verbenaceae, and Scrophulariaceae. Iridoids have the potential of modulating many biological events in various diseases. This review highlights the multitarget potential of iridoids and includes a compilation of recent publications on the pharmacology of iridoids. Several in vitro and in vivo models used, along with the results, are also included in the paper. This paper's systematic summary was created by searching for relevant iridoid material on websites such as Google Scholar, PubMed, SciFinder Scholar, Science Direct, and others.The compilation will provide the researchers with a thorough understanding of iridoid and its congeners, which will further help in designing a large number of potential compounds with a strong impact on curing various diseases.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Ejaz, Syeda Abida, Aftab Farid, Seema Zargar, Pervaiz Ali Channar, Mubashir Aziz, Tanveer A. Wani, Hafiz Muhammad Attaullah et al. « Computational and theoretical chemistry of newly synthesized and characterized 2,2’-(5,5’-(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-acetamides ». BMC Chemistry 17, n^o 1 (14 août 2023). http://dx.doi.org/10.1186/s13065-023-01011-3.

Texte intégral

Résumé :

AbstractEnergetic heterocycles, including pyridines, triazoles, and tetrazoles, exhibit greater density, heats of formation, and oxygen balance compared to their carbocyclic counterparts, making them a promising approach for synthesizing novel bis-tetrazole acetamides. Synthesized compounds A-F, some of which feature a chlorine atom attached to the phenyl ring, serve as valuable synthons for aryl coupling reactions. Analysis via 1H-NMR and 13C-NMR spectroscopy, as well as density functional considerations through B3LYP functional correlation with 6-311 + + G(d) and 6-31G(d) basis set, revealed the observed LUMO/HOMO energies and charge transfer within the molecule. Additionally, the dipole moment, chemical hardness, softness, ionization potential, local reactivity potential via Fukui indices and thermodynamic properties (entropy, enthalpy, and Gibbs free energy) of the molecule were calculated through density functional theory studies. In addition, Molecular Docking studies were conducted to investigate the anti-cancer potential of synthesized heterocyclic compounds against caspase 3, NF-KAPPA-B and P53 protein. Molecular docking analysis demonstrated a potent interaction between 2,2’-(5,5’-(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-(2,4-dinitrophenyl) acetamides (6d) and TP53 and NF-KAPPA-B with binding energies of − 11.8 kJ/mol and − 10.9 kJ/mol for TP53 and NF-KAPPA-B, respectively. Similarly, 2,2’-(5,5’–(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-(2-chlorophenyl) acetamides (6f) exhibited a strong interaction with caspase-3 with binding energy of -10.0 kJ/mol, indicating their potential as therapeutic agents against these proteins. Furthermore, the findings of current study was further strengthen by 100 ns molecular dynamics (MD) simulations. Finally, theoretical studies of oxygen balance and nitrogen percentage suggest that these molecules can be utilized as energetic materials. Graphical Abstract

Styles APA, Harvard, Vancouver, ISO, etc.

48

Liu, Min, Nuo Yan, Haowen Tian, Bo Li et Dongbing Zhao. « Ring Expansion toward Disila‐carbocycles via Highly Selective C−Si/C−Si Bond Cross‐Exchange ». Angewandte Chemie, 22 février 2024. http://dx.doi.org/10.1002/ange.202319187.

Texte intégral

Résumé :

Herein, we successfully inhibited the preferential homodimerization and C−Si/Si−H bond cross‐exchange of benzosilacyclobutenes and monohydro‐silacyclobutanes and achieved the first highly selective C−Si/C−Si bond cross‐exchange reaction by deliberately tuning the Ni‐catalytic system, which constitutes a powerful and atom‐economical ring expansion method for preparing medium‐sized cyclic compounds bearing two silicon atoms at the ring junction, which are otherwise inaccessible. The DFT calculation explicitly elucidated the pivotal role of Si−H bond at silacyclobutanes and the high ring strain of two substrates in realizing the two C−Si bonds cleavage and reformation in the catalytic cycle.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Liu, Min, Nuo Yan, Haowen Tian, Bo Li et Dongbing Zhao. « Ring Expansion toward Disila‐carbocycles via Highly Selective C−Si/C−Si Bond Cross‐Exchange ». Angewandte Chemie International Edition, 22 février 2024. http://dx.doi.org/10.1002/anie.202319187.

Texte intégral

Résumé :

Herein, we successfully inhibited the preferential homodimerization and C−Si/Si−H bond cross‐exchange of benzosilacyclobutenes and monohydro‐silacyclobutanes and achieved the first highly selective C−Si/C−Si bond cross‐exchange reaction by deliberately tuning the Ni‐catalytic system, which constitutes a powerful and atom‐economical ring expansion method for preparing medium‐sized cyclic compounds bearing two silicon atoms at the ring junction, which are otherwise inaccessible. The DFT calculation explicitly elucidated the pivotal role of Si−H bond at silacyclobutanes and the high ring strain of two substrates in realizing the two C−Si bonds cleavage and reformation in the catalytic cycle.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Miguélez, Rubén, Pablo Barrio et José M. González. « Recent Advances in the Catalytic Synthesis of the Cyclopentene Core ». Chemical Record, 11 octobre 2023. http://dx.doi.org/10.1002/tcr.202300254.

Texte intégral

Résumé :

AbstractFive‐membered carbocycles are ubiquitously found in natural products, pharmaceuticals, and other classes of organic compounds. Within this category, cyclopentenes deserve special attention due to their prevalence as targets and as well as key intermediates for synthesizing more complex molecules. Herein, we offer an overview summarizing some significant recent advances in the catalytic assembly of this structural motif. A great variety of synthetic methodologies and strategies are covered, including transition metal‐catalyzed or organocatalyzed processes. Both inter‐ and intramolecular transformations are documented. On this ground, our expertise in the application of C−H functionalization reactions oriented towards the formation of this ring and its subsequent selective functionalization is embedded.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Carbocyclic ring compounds »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres