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Most Cited Articles

The Top 20 Cited Articles

The most cited articles are updated on a monthly basis and available as Last 3 Years. Citation data is obtained through CrossRef's Cited-Linking service.

Note: The Top 20 Citations are published across all volumes.

Short Paper | Regular issue | Vol 91, No. 9, 2015, pp.1809-1815
Published online: 4 August, 2015
DOI: 10.3987/COM-15-13285
Viridobrunnines A and B, Antimicrobial Phenoxazinone Alkaloids from A Soil Associated Streptomyces sp.

Xiu Mei Zhang, Xu Liu, Zhe Wang, Zhen Hua Tian, and Wei Dong Xie*

*Department of Pharmacy, Marine College, Shangdong University at Weihai, Wenhua Xilu 180, Weihai 264209, China

Abstract

Chemical investigation of a Streptomyces sp. strain designated A1302 isolated from soil sample led to the discovery of two new phenoxazinone alkaloids, viridobrunnines A and B (1 - 2), along with two known analogues exfoliazone (3) and chandrananimycin D (4). Their structures were established by means of spectroscopic methods. The antibacterial and antifungal activity of isolated compounds was assayed. Viridobrunnine B (2) exhibited potent antibacterial activity against Bacillus subtilis with inhibition zone from 13 mm to 15 mm.

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Review | Special issue | Vol 28, No. 1, 1989, pp.489-519
Published online: 1 January, 1970
DOI: 10.3987/REV-88-SR1
Recent Developments of Free-Radical Substitutions of Heteroaromatic Bases

Francesco Minisci,* Elena Vismara, and Francesca Fontana

*Dipartimento di Chimica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

Abstract

The most recent mechanistic and synthetic aspects of the substitution of protonated heteroaromatic bases by nucleophilic carbon-centered radicals are reviewed. From mechanistic point of view the following aspects are discussed; i ) Structurereactivity relationship; i i ) Rearomatization of the radical adducts; iii) Solvent and isotope effects; iv) Overlap area with ionic reactions. The synthetic developments concern the following topics: i) Selectivity with carbonyl radicals; ii) Alkyl iodides as sources of alkyl radicals; iii) Alkylation by carboxylic acids; iv) Vinylation by olefins; v) Oxyalkylation by ethers; vi) Catalytic processes; vii) Substitution with strongly nucleophilic radicals.

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Review | Special issue | Vol 56, No. 1-2, 2002, pp.633-692
Published online: 1 January, 1970
DOI: 10.3987/REV-01-SR(K)2
Recent Progress in the Chemistry of Polyacylated Anthocyanins as Flower Color Pigments

Toshio Honda* and Norio Saito

*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

It is recognized that the bluing effect and stabilization of flower colors will remarkably depend on the number of aromatic acids presented in the polyacylated anthocyanins. Although polyacyl functions would be considered to contribute strongly in the bluing of the flower color at the early stage of the investigation of polyacylated anthocyanin chemistry, the stabilization of flower color is considered to be another important objective by the presence of these aromatic acids at the present time. Since aromatic acids in the polyacylated anthocyanins are obviously linked with the sugar residues through the ester bonds, the polyacylated anthocyanins are classified into seven types by the substitution pattern of acyl functions, and the effect of the stacking structures of polyacyl anthocyanins on the stabilization of the flower color depending on the substitution pattern of acyl groups will be discussed. The physicochemical properties (NMR, UV-VIS spectra) in relation to the stability of the anthocyanins will also be discussed.

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Review | Special issue | Vol 49, No. 1, 1998, pp.531-556
Published online: 1 January, 1970
DOI: 10.3987/REV-98-SR2
Survey of Oxygenated 2,11-Cyclized Cembranoids of Marine Origin

Patrick Bernardelli and Leo A. Paquette*

*Evans Chemical Laboratories, The Ohio State University, Columbus, OH 43210, U.S.A.

Abstract

The structure, source, and biological activities of the many known members of the four classes of oxygenated 2,11-cyclized cembranoid natural products are compiled in tabular form. The cladiellins, briarellins, asbestinins, and sarcodictyins have been purposefully organized to highlight biological activity interrelationships.

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Review | Special issue | Vol 40, No. 1, 1995, pp.477-500
Published online: 1 January, 1970
DOI: 10.3987/REV-94-SR2
Cyclic Carboxylic Imide Structures as Structure Elements of High Stability. Novel Developments in Perylene Dye Chemistry

Heinz Langhals

*Institut für Organische Chemie, Universität München, Karlstrasse 23, D-80333 München, Germany

Abstract

Cyclic carboxylic imides are structure elements in aromatic heterocycles with high persistency. Their attachment to perylene leads to the perylene dyes; the synthesis and unique properties of the dyes are reported and discussed. An extension of the principle to other aromatics is made.

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Paper | Regular issue | Vol 71, No. 9, 2007, pp.1975-1990
Published online: 15 June, 2007
DOI: 10.3987/COM-07-11088
From Haloquinolines and Halopyridines to Quinoline- and Pyridinesulfonyl Chlorides and Sulfonamides

Andrzej Maslankiewicz,* Krzysztof Marciniec, Maciej Pawlowski, and Pawel Zajdel

*Department of Organic Chemistry, The Medical University of Silesia
Jagiellonska 4, 41-200 Sosnowiec, Poland

Abstract

The action of sodium methanethiolate (in boiling DMF) towards haloazines (i.e. chloro- or bromo-pyridines and quinolines) (1) (with halogen substituent in non-aza-activated position) causes sequentially halogen ipso-substitution to methylthioazines (2) and then S-demethylation to azinethiolates (3A), which were: i) subjected to S-methylation, ii) oxidized to diazinyl disulfides (4) and iii) oxidatively chlorinated to azinesulfonyl chlorides (5). α- and β-pyridine- and quinolinesulfonyl chlorides (5a, 5c, 5d and 5f) were prepared by oxidative chlorination of respective disulfides (4) performed in conc. hydrochloric acid and characterized by 1H and 13C NMR spectra. All azinesulfonyl chlorides (5) were effectively converted to corresponding azinesulfonamides (6).

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Paper | Special issue | Vol 77, No. 2, 2009, pp.1307-1321
Published online: 28 October, 2008
DOI: 10.3987/COM-08-S(F)116
New [11C]Phosgene Based Synthesis of [11C]Pyrimidines for Positron Emission Tomography

Koh-ichi Seki,* Ken-ichi Nishijima, Kimihito Sanoki, Yuji Kuge, Masayuki Takahashi, Hiromichi Akizawa, Nagara Tamaki, Leonard I. Wiebe, and Kazue Ohkura*

*Central Institute of Radio Isotope Science, Hokkaido University, Kita 15 Nishi 7, Kita-ku, Sapporo, Hokkaido 060-0815, Japan

Abstract

Thymine, 5-FU, and uracil were successfully synthesized through a procedure involving a cyclocondensation of triphosgene with newly developed α-substituted β-aminoacrylamides intermediates (1a, X = Me; 1b, X = F; 1c, X = H). The radioligands [2-11C]thymine and [2-11C]5-fluorouracil were synthesized in high radiochemical yields in 16-17 minutes from the end of bombardment by applying the cyclocondensation method with [11C]COCl2.

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Paper | Special issue | Vol 82, No. 1, 2010, pp.663-687
Published online: 8 July, 2010
DOI: 10.3987/COM-10-S(E)42
Synthesis and Anti-HIV Activity of New 3’-O-Phosphonomethyl Nucleosides

Michal Cesnek and Piet Herdewijn*

*K.U. Leuven, Rega Institute for Medical Research, Minderbroedersstraat 10, B-3000 Leuven, Belgium

Abstract

The synthesis of 4’(S)-ethynyl-2’-deoxythreosyl and β-D-galactofuranose nucleosides starting from D-galactose is described. The nucleobase is introduced using Vorbruggen glycosylation. The 4’(S)-ethynyl derivatives are obtained by selective oxidation of vicinal diol to the aldehyde and subsequent Bestmann modification of Seyferth-Gilbert homologation. All compounds were evaluated for activity against HIV (MT4 cells), RSV (Hep2 cells) and HCV (HCV replicon cells), however, none of these compounds demonstrate biological activity.

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Short Paper | Regular issue | Vol 96, No. 12, 2018, pp.2126-2134
Published online: 20 December, 2018
DOI: 10.3987/COM-18-14002
Multigram-Scale and Column Chromatography-Free Synthesis of L-Azetidine-2-carboxylic Acid for the Synthesis of Nicotianamine and Its Derivatives

Tomohiro Takaishi, Kyosuke Wakisaka, Christopher J Vavricka, Hiromasa Kiyota, and Minoru Izumi*

*Graduate School of Environmental and Life Science, Okayama University, 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan

Abstract

Multigram-scale synthesis of L-azetidine-2-carboxylic acid from L-aspartic acid was achieved in 13 conventional synthetic steps, without the need for purification by silica-gel column chromatography and expensive reagents. Nicotianamine and its fluorescence-labeled derivatives could be obtained from this synthetic strategy.

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Communication | Regular issue | Vol 94, No. 3, 2017, pp.441-447
Published online: 17 March, 2017
DOI: 10.3987/COM-16-13642
Stereoselective Aza-Henry Reaction of 3-Nitro-dihydro-2(1H)-quinolones with N-Boc-Aldimines under the Catalysis of Chiral Ammonium Betaines

Daisuke Uraguchi, Masahiro Torii, Kohsuke Kato, and Takashi Ooi*

*Institute of Transformative Bio-Molecules (WPI-ITbM) and Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan

Abstract

A highly enantioselective aza-Henry reaction between 3-nitro-dihydro-2(1H)-quinolones and N-Boc-aldimines was developed by using a chiral ammonium betaine as a catalyst. This protocol provides a direct synthetic method for accessing hydroquinoline derivatives possessing a tetrasubstituted stereogenic center at the C3 position and casts light on the utility of the α-functionalization of dihydroquinolones.

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Review | Regular issue | Vol 102, No. 10, 2021, pp.1861-1893
Published online: 28 April, 2021
DOI: 10.3987/REV-20-953
Recent Achievements in the Synthesis of Heterocyclic Compounds by Phthalhydrazide-Based Multicomponent Reactions

Ghodsi Mohammadi Ziarani,* Negar Jamasbi, and Fatemeh Mohajer

*Department of Chemistry, Faculty of Physic and Chemistry, Alzahra University, Tehran, Iran. P. O. Box 1993893973

Abstract

Phthalhydrazide is one of the useful starting material toward the synthesis of heterocyclic compounds, and considered as a valuable structural unit in organic synthesis due to its significant pharmacological and biological activities. There are many multicomponent reactions using phthalhydrazide under different conditions. This review article aims to give an overview of recent applications of phthalhydrazide in the multicomponent reactions during the period of 2006 to 2021.

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Review | Regular issue | Vol 91, No. 2, 2015, pp.239-264
Published online: 27 January, 2015
DOI: 10.3987/REV-14-811
Synthesis of Triazole, Indole, and Five or Six-Membered Saturated Heterocyclic Compounds

Yasunari Monguchi,* Yoshinari Sawama, and Hironao Sajiki*

*Laboratory of Organic Chemistry, Department of Pharmaceutical Sciences, Gifu Pharmaceutical University, 1-25-4 Daigakunishi, Gifu 501-1196, Japan

Abstract

Heterogeneously-catalyzed synthetic methods for the preparation of 1,2,3-triazoles, indolines, indoles, and saturated heterocyclic compounds, such as piperidine and pyrrolidine, are demonstrated. Triazoles are intermolecularly synthesized by the 1,3-dipolar cycloaddition of alkynes with azides using heterogeneous copper catalysts. Solvent-free triazole syntheses are also described. Inter- and intramolecular annulations as indole syntheses are summarized; e.g., a palladium on carbon (Pd/C)-catalyzed YamanakaLarock method affords 2- or 2,3-substituted indoles from 2-iodoaniline derivatives and mono- or di-substituted alkynes; an intramolecular Pd/C-catalyzed BuchwaldHartwig reaction of 2-bromophenethylamine derivatives temperature-dependently affords indolines or indoles. Pd/C can also catalyze an intermolecular aromatic amination of bromoarenes with indoles to generate the corresponding N-arylindoles. The application of the hydrogenation technology using 10% Pd/C, 10% rhodium on carbon (Rh/C), or 10% ruthenium on carbon (Ru/C) as a catalyst is finally introduced for the synthesis of indole by the intramolecular hydrogenative N-alkylation of 2-cyanomethylaniline and piperidine, pyrrolidine, and tetrahydrofuran derivatives by the arene hydrogenation of pyrridine, pyrrole, and furan derivatives under relatively mild conditions, respectively.

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Note | Regular issue | Vol 57, No. 2, 2002, pp.353-356
Published online: 1 January, 1970
DOI: 10.3987/COM-01-9410
The Crystal and Molecular Structure of 2,3,5,6-Tetraphenyl-1,4-dithiin

Ian W. Jones and Patrick E. Hoggard*

*Department of Chemistry, Santa Clara University, 500 El Camino Real, Santa Clara, California 95053-270, U.S.A.

Abstract

The phenyl rings in 2,3,5,6-tetraphenyl-1,4-dithiin have neither of the two most obvious configurations: all perpendicular to the dithiin ring (paddlewheel), or parallel to the dithiin double bonds (butterfly). Instead, there are two phenyls in each orientation.

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Paper | Regular issue | Vol 53, No. 7, 2000, pp.1533-1549
Published online: 1 January, 1970
DOI: 10.3987/COM-00-8922
LI-F Antibiotics, a Family of Antifungal Cyclic Depsipeptides Produced by Bacillus polymyxa L-1129

Jun Kuroda, Toshio Fukai, Masataka Konishi, Jun Uno, Keiji Kurusu, and Taro Nomura*

*Faculty of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan

Abstract

Twelve antifungal depsipeptide antibiotics named as LI-F03a, LI-F03b, LI-F04a, LI-F04b, LI-F05a, LI-F05b, LI-F06a, LI-F06b, LI-F07a, LI-F07b, LI-F08a and LI-F08b have been isolated from the fermentation broth of Bacillus polymyxa L-1129 by use of extensive preparative HPLC. Not only their intrinsic antifungal and anti-Gram positive bacterial activity, they also showed unique synergistic antifungal effect in combination with the azole group antifungal agents. The structural studies disclosed that they are cyclic depsipeptides composed of six amino acids (three of them, L-threonine, D-allo-threonine and D-alanine being in common among all components and other three amino acids variable) on which is substituted by a 15-guanidino-3-hydroxypentadecanoic acid.

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Paper | Special issue | Vol 93, No. 2, 2016, pp.705-713
Published online: 6 January, 2016
DOI: 10.3987/COM-15-S(T)60
Facile Synthesis of 5- to 7-Membered Benzolactam Compounds via Strongly Facilitated Electrophilic Aromtic Substitution Reaction

Hiroaki Kurouchi, Yuko Otani, and Tomohiko Ohwada*

*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

We employed our system to activate aromatic ring-tethered carbamate compounds with trifluoromethanesulfonic acid to obtain benzolactams with 5- to 7-membered rings, and examined the substrate scope and limitations of this activation method. In 5-membered ring formation, a halogen group on the aromatic ring did not greatly affect the reaction yield, but other electron-donating groups inhibited the cyclization reaction, and various side-reactions occurred. In 7-membered ring formation, eletron-donating groups on aromatic ring promoted the cyclization reaction, but cyclization of electron-deficient aromatic rings did not proceed well. The 6-membered ring formation reaction showed the greatest substrate generality.

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Communication | Regular issue | Vol 27, No. 9, 1988, pp.2107-2110
Published online: 1 January, 1970
DOI: 10.3987/COM-88-4690
Kinetic Resolution of 2-Furylcarbinols Using the Sharpless Oxidation and Its Application to the Synthesis of (5R,6S)-6-Acetoxy-5-hexadecanolide

Tetsuji Kametani,* Masayoshi Tsubuki, Yoko Tatsuzaki, and Toshio Honda

*Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

Kinetic resolution of 2-furylcarbinols employing 10 mol % of Ti(0iPr)4 in the presence of molecular sieves 3A under the Sharpless oxidation condition generally affords corresponding optically actlve 2-furylcarbinols in a range of 80-98% ee. Application of the optically active 1f to the synthesis of (5R,6S)-6-acetoxy-5-hexadecanolide (8), the major component of the oviposition attractant pheromone of the mosquito Culex pipens fatigans, has also been achieved.

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Paper | Special issue | Vol 79, No. 1, 2009, pp.681-693
Published online: 21 November, 2008
DOI: 10.3987/COM-08-S(D)35
Facile Syntheses of Three Ahp-Type Building Blocks with Complementary Reactivity

Wen Chen, Xiao Zheng, Yuan-Ping Ruan, and Pei-Qiang Huang*

*Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China

Abstract

Two protected 3-amino-6-hydroxy-2-piperidone derivatives (Ahp, 12 and 6), as well as a thioether analogue (7) were synthesized starting from L-glutamic acid in four, five, and six steps respectively. The Ahp derivatives 12 and 6 are not only the structural feature found in many naturally occurring bioactive depsipeptides, but also precursors of the N-acyliminium such as D; while the (S)-thioether 7 was shown to be an effective synthetic equivalent of the novel 2-piperidone N-α-carbanion E via the lithium-naphthalenide (LN)-mediated reductive lithiation, capable of reacting with carbonyl compounds without an acidic α–position to give the α-hydroxyalkylation products.

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Paper | Regular issue | Vol 85, No. 2, 2012, pp.365-381
Published online: 22 December, 2011
DOI: 10.3987/COM-11-12392
Hydrolysable Tannins Isolated from Syzygium aromaticum: Structure of a New C-Glucosidic Ellagitannin and Spectral Features of Tannins with a Tergalloyl Group

Li-Ming Bao, _ Eerdunbayaer, Akiko Nozaki, Eizo Takahashi, Keinosuke Okamoto, Hideyuki Ito, and Tsutomu Hatano*

*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Eighteen hydrolysable tannins, including a new C-glucosidic tannin named aromatinin A (1), were isolated from an aqueous acetone extract of dried flower buds of Syzygium aromaticum Merr. et Perry. We determined that 1 had a gallic acid C-glucoside structure, based on the spectral data and synthesis from casuarinin (18) and gallic acid (20). This is a rare example of hydrolysable tannins with gallic acid C-glucoside structure. We also report the 1H nuclear magnetic resonance (NMR) spectral features of syzyginin A (2), bicornin (3), and platycaryanin A (4), which were also isolated from S. aromaticum, based on their structures with a tergalloyl group or its depsidone form. The remaining known compounds were identified as alunusnin A (5), rugosin C (6), 1,2,3-tri-O-galloyl-β-D-glucose (7), 1,2,3,6-tetra-O-galloyl-β-D-glucose (8), tellimagrandin II (9), casuarictin (10), heterophylliin D (11), rugosin D (12), rugosin F (13), euprostin A (14), 1,2-di-O-galloyl-3-O-digalloyl-4,6-O-(S)-hexa- hydroxydiphenoy-β-D-glucose (15), alienanin B (16), squarrosanin A (17), and 18. The antifungal effects of hydrolysable tannins, 9, 12, and 18 against Candida strains are also described.

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Paper | Special issue | Vol 99, No. 2, 2019, pp.942-957
Published online: 14 December, 2018
DOI: 10.3987/COM-18-S(F)60
Synthesis, Conformation, and Biological Activities of a Des-A-Ring Analog of 18-Deoxy-Aplog-1, a Simplified Analog of Debromoaplysiatoxin

Yoshiki Ashida, Ryo C. Yanagita,* Yasuhiro Kawanami, Mutsumi Okamura, Shingo Dan, and Kazuhiro Irie

*Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kagawa 761-0795, Japan

Abstract

10-Me-Aplog-1 as a simplified analog of tumor-promoting debromoaplysiatoxin and a potent activator of protein kinase C (PKC) is a promising chemotherapeutic agent. In this study, we synthesized a des-A-ring analog (4) of 18-deoxy-aplog-1 as a synthetically-accessible analog. Compound 4 retained the conformation of the PKC-recognition part of aplogs. Moderate affinity for conventional PKC isozymes (α, β, γ) and anti-proliferative activity against NCI-H460 (lung) and MKN45 (stomach) human cancer cell lines were observed. The results suggest that 4 could serve as a lead compound for the development of conventional PKC isozyme-selective chemotherapeutic agents.

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Short Paper | Regular issue | Vol 102, No. 9, 2021, pp.1797-1802
Published online: 2 July, 2021
DOI: 10.3987/COM-21-14499
New and Practical Synthesis of GS-441524, the Key Intermediate of Remdesivir

Bo Li, Han Wang,* Cong Sun, Sheng Lu, LinLin Kang, and Shun Jiang

*College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China

Abstract

A new and practical synthesis of GS-441524, the key intermediate for remdesivir, is developed. 4-Amino-7-iodopyrrolo[2,1-f][1,2,4]triazine is protected by DMF-DMA, and reacted with 2,3,5-tri-O-benzyl-D-ribonolactone to give the product in 61% isolated yield. The next cyanation and debenzylation are carried out at −30 °C successively in 67% yield over two steps with >99% purity (HPLC). Purification methods of the intermediates and the final product involved in the route are developed.

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