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18 data found. 1 - 18 listed

Published online: 12th August, 2022

Review | Regular issue | Prepress
DOI: 10.3987/REV-22-986
Understanding the Diversity and Molecular Basis of Biosynthesis of Heterocyles in Natural Products Produced by Actinobacteria

Yohei Katsuyama*

*Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan

Abstract

Many of the natural products produced by actinomycetes have useful biological activities including antibiotic, antitumor and immunosuppressant activities, reflecting their structural diversity. In addition, many of them have heterocyclic rings in their structures, and these rings are considered to be important for their biological activities. Various chemical reactions and enzymes catalyzing them are used for their formation reactions. In this review, our recent examples of biosynthetic studies on the natural product with heterocycles in actinomycetes are summarized. These include indoline and tetrahydroquinoline ring formation using the nitrene-forming reaction found in the biosynthetic pathway of benzastatin, oxazoline ring formation in nonribosomal peptide synthetases and polyketide-derived piperidine alkaloid biosynthesis. These studies are expected to provide novel insights into enzyme chemistry as well as a new idea for synthetic organic chemists.

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Published online: 10th August, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14718
Microwave-Induced One Step Synthesis of Structurally Diverse Linear Indoloquinolines: Concise Synthesis of Norneocryptolepine

Krisztián Biró, János Tatai, Bence Pollák, Márk Molnár, and Miklós Nyerges*

*Servier Research Institute of Medicinal Chemistry, 7, Záhony utca, 1031, Budapest, Hungary

Abstract

A general and efficient synthesis of diverse tetra- and pentacyclic indolo[2,3-b]quinoline derivatives was achieved through a microwave assisted, metal-free, base catalyzed domino Knoevenagel condensation, intramolecular cyclization process starting from simple oxindole and 2-amino-arylaldheydes. This approach provides a straightforward, atom-economical and concise route to access a diverse range of otherwise not easily available heterocycles in excellent yields with good tolerance of functional groups.

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Published online: 9th August, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14707
An Improved and Practical Synthesis of Rivaroxaban

Shovkat Olimjonov, Xiaojun Yang, Yongjian Liu, Abdullajon Odilov, Hongjian Qin, Tianwen Hu, Sharafitdin Mirzaakhmedov, Yuanchao Xie, Fuqiang Zhu,* and Jingshan Shen*

*Topharman Shanghai Co., Ltd., Building 1, No.388 Jialilue Road, Zhangjiang Hitech Park, Shanghai 201203, People’s Republic of China

Abstract

Herein we report the development of an improved and practical synthesis of rivaroxaban, an oral anticoagulant drug as a factor Xa inhibitor. The synthesis of rivaroxaban was accomplished by five steps with a total yield of 68.5% on the 220 g scale with a purity of ≥ 99% (single impurity ≤ 0.10%). The epoxy ring-opening reaction was significantly improved with the addition of the magnesium salt. Then, a plausible mechanism was proposed according to our experimental results. Three process-related impurities were identified and controlled by process optimization. The optimized synthesis is expected to offer the technical support for large scale production.

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Published online: 9th August, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14720
Direct Arylation of Furoxan Using Potassium Aryltrifluoroborates

Chenlu Dong, Masahiko Hayashi, and Ryosuke Matsubara*

*Department of Chemistry , Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

Direct arylation of a furoxan ring with potassium aryltrifluoroborates is proposed. A series of aryl-substituted furoxan derivatives have been constructed through the formation of a new C−C bond via a radical pathway. The plausible reaction mechanism is proposed based on the DFT-calculation study.

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Published online: 8th August, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14705
Facile Protocol for the Synthesis of Electron-Rich Benzimidazole Derivatives

Robert D. Pike and Brian E. Love*

*Department of Chemistry, East Carolina University, Greenville, NC, 27858, U.S.A.

Abstract

A protocol is reported which allows preparation of electron-rich benzimidazole derivatives in good yield. The reaction proceeds directly from dinitrobenzene derivatives without need of isolation of air-sensitive diamines.

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Published online: 29th July, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14696
The Continuous-Flow Synthesis of 1H-Indazoles via Reaction of o-Fluorobenzaldehydes with tert-Butyl Carbazate under High Temperature

Wenjie Ye, Kai Zhu, Yiping Huang, Chuansong Duanmu, Yanxing Li, Jin Li, Weichuan Xu, and Feng Zhou*

*National & Local Joint Engineering Research Center for Deep Utilization Technology of Rock-salt Resource, Faculty of Chemical Engineering, Huaiyin Institute of Technology, Huai’an 223003, P. R. China

Abstract

Large amounts of 1H-indazoles have been developed and widely used in the production of diverse drugs. The reaction of 4-bromo-2,6-difluorobenzaldehyde with tert-butyl carbazate was selected as model transformation for the application of continuous-flow strategy to realize the efficient syntheses of 1H-indazoles in a highly controlled and safe manner. Various conditions (reaction temperature, residence time, solvent amount, the amount of tert-butyl carbazate, water content) were investigated under continuous-flow conditions to elucidate the benefits of using the continuous-flow strategy. The Box-Behnken design in response surface methodology was employed for the optimization of reaction conditions, and over 85% yield of 6-bromo-4-fluoro-1H-indazole could be achieved. Furthermore, the generality of the reaction conditions found optimal for the synthesis of 6-bromo-4-fluoro-1H-indazole was evaluated for the synthesis of several different 1H-indazoles.

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Published online: 26th July, 2022

Review | Regular issue | Prepress
DOI: 10.3987/REV-22-985
Total Syntheses of Conhydrines via Ruthenium-Catalyzed Ring-Closing Metathesis (RCM) Reactions

Tian Jin,* Lu Zhao,* Hong-Ping Wang, Chichong Lu,* Zong-He Li, Zhe-Bin Zheng, and Won-Hun Ham*

*Sichuan Industrial Institute of Antibiotics, School of Pharmacy, Chengdu University, Huaguan Road 168, Chengdu City, China

Abstract

Conhydrines are extremely interesting target molecules in organic synthesis because of their unique structural motifs and potent bioactivities. The ring-closing metathesis (RCM) reaction has received considerable attention for a long time. In this review, we highlight 13 total syntheses of conhydrines by using RCM reaction as the key step from different research groups during the period 2000 to 2021.

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Published online: 26th July, 2022

Communication | Regular issue | Prepress
DOI: 10.3987/COM-22-14714
Direct β-Alkenylation of Thiophenes with Alkenyl Halides Catalyzed by a Dinuclear Palladium Complex

Nozomi Asahara and Naofumi Tsukada*

*Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan

Abstract

Direct alkenylation of thiophenes with iodoalkenes proceeded in the presence of a dinuclear palladium complex formed by a chelate-bridging ligand. In most reactions, β-alkenylthiophenes were obtained with good to high regioselectivity.

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Published online: 22nd July, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14697
An Efficient Method for the Synthesis of N-Aryl Substituted C1-Functionalized 1,2,3,4-Tetrahydroisoquinolines

Hairong Luo,* Fen Tian, Yi He, Xurong Liu, Jing Li, and Meihang Chen*

*College of Material and Chemical Engineering, Tongren University, Tongren,Guizhou 554300, China

Abstract

An efficient and facile cyclic iminium-ion-based strategy has been developed for the synthesis of structurally diverse N-aryl substituted C1-functionalized THIQs. Cyclic iminium ions generated in situ from 2-(2-bromomethyl)benzaldehyde reacted with acetone to furnish ketone moiety at C-1 position in THIQs in moderate to good yields.

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Published online: 20th July, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14713
New Anti-TMV Isochromenes from Nicotiana tabacum-Derived Endophytic Fungus Aspergillus versicolor

Qiu-Fen Hu, Ling-Fang Zhang, Guang-Hai Zhang, Mei-Fen Bao, Yin-Ke Li, Dong Miao, Yu-Ping Wu, Gang Du,* and Guang-Hui Kong*

*Key Laboratory of Chemistry in Ethnic Medicinal Resources, Yunnan Minzu University, Kunming 60500, P. R. China

Abstract

Three new isochromenes, versicolols G-I (1-3), together with four known analogues (4-7) were isolated from the fermentation products of a Nicotiana tabacum-derived endophytic fungus Aspergillus versicolor. Their structures were elucidated by spectroscopic methods, including extensive 1H, 13C, and 2D-NMR techniques. Compounds 1-3 were also tested for their anti-tobacco mosaic virus (anti-TMV) activities, and the results revealed that compound 1 exhibited high anti-TMV activity with inhibition rate of 41.6%, and this rate are higher than that of positive control. Compounds 2 and 3 also showed potential anti-TMV activities with inhibition rates of 22.8 and 26.5%, respectively.

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Published online: 15th July, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14699
Molecular Iodine Mediated Synthesis of 2,4,5-Trisubstituted Imidazoles Commencing from α-Methylene Ketones and Benzylic Primary Alcohols Using a One-Pot, Two-Step Approach

Lindokuhle P. Mabizela and Vineet Jeena*

*School of Chemistry and Physics, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, 3209, South Africa

Abstract

A simple one-pot, two-step approach to 2,4,5-trisubstituted imidazoles has been developed commencing from α-methylene ketones and primary alcohols. Using an environmentally friendly, inexpensive, and readily available iodine-based system, a series of trisubstituted imidazoles were prepared in moderate to good yields under mild reaction conditions.

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Published online: 15th July, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14700
Reactivity of 4-Bromoacetyl-1,2,3-triazoles towards Amines and Phenols: Synthesis and Antimicrobial Activity of Novel Heterocycles

Bakr F. Abdel-Wahab, Hanan A. Mohamed, Abdelbasset A. Farahat, Benson M. Kariuki, and Gamal A. El-Hiti*

*Department of Optometry, College of Applied Medical Sciences, King Saud University, P.O. Box 10219, Riyadh 11433, Saudi Arabia

Abstract

The reactivity of 4-bromoacetyl-1H-1,2,3-triazoles towards amines and phenols was studied. Reaction of 4-bromoacetyl-1H-1,2,3-triazole (1a; R = H) with benzylamine (2) in the absence of any catalyst unexpectedly afforded heterocycle 2,5-bis(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)pyrazine (4) in 50% yield. Additionally, the reaction of 1b (R = Br) with 4-bromoaniline and of 1c (R = Me) or 1d (R = NO2) with 1H-benzotriazole in basic media gave the expected aminoketone products 8 and 9a or 9b in high yields. Furthermore, the reaction of 1c (R = Me) or 1e (R = Cl) with phenol or β-naphthol in basic media led to the production of keto-ethers 10 or 11, respectively in an excellent yield. Compound 10 showed the highest inhibitory effect against the growth of the tested pathogens.

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Published online: 15th July, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14703
Synthesis of 2,3-Anthracenedicarboxylic-Acid-Derived Fluorophore and Chemiluminophore Incorporating Dipicolylaminomethyl Receptors, and Their Luminescence Responses to Metal Ions

Naomi Yamazaki, Ayako Matsui, Kyosuke Satake, and Hideki Okamoto*

*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

2,3-Anthracenedicarboxylic-acid-derived carboximide 1 and cyclic-hydrazide 2, incorporating dipicolylaminomethyl receptors, have been respectively prepared as novel fluorescence and chemiluminescence probes for metal cations. Carboximide 1 was essentially non-fluorescent in acetonitrile whereas it produced intense fluorescence (λFLmax 470 nm) upon addition of Zn2+ (off–on response). Cyclic-hydrazide 2 gave off blue chemiluminescence emission (λCLmax 465 nm) after addition of alkaline H2O2 and iodide ion in dimethyl sulfoxide. Addition of metal cations, e.g. Zn2+, into the chemiluminescence system resulted in significant quenching of the chemiluminescence (on–off response). Therefore, the effects of the metal cation on the chemiluminescence behavior of cyclic-hydrazide 2 showed clear contrast to those on the fluorescence behavior of carboximide 1.

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Published online: 13th July, 2022

Communication | Regular issue | Prepress
DOI: 10.3987/COM-22-14698
Facile and Efficient N-Boc Deprotection of Amide and Sulfonamide under Microwave Irradiation in Water

Zhi-you Huang,* Wen-sheng Li, Jia Xu, Bing-rong Xiang, Min-xin Li, Li-jun Chen, and Ye-she Wang

*College of Urban and Rural Construction, Shaoyang University, Shaoyang, 422000, P.R.China

Abstract

A facile and efficient microwave-assisted N-Boc deprotection of amide and sulfonamide in water was developed. With environmentally friendly, operational-simplicity, good substrate scope and excellent product yields, this methodology is superior to the existing approach. Significantly, the target compound was obtained after filtration and dry.

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Published online: 12th July, 2022

Review | Regular issue | Prepress
DOI: 10.3987/REV-22-983
Total Synthesis of (−)-Exiguolide, a Potent Anticancer Marine Macrolide

Haruhiko Fuwa*

*Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan

Abstract

(−)-Exiguolide is a marine macrolide natural product, isolated by Ohta and co-workers from a rare marine sponge, Geodia exigua Thiele, collected off Amami-Oshima, Japan. The structural complexity and potent anticancer activity of this natural product spurred the interest of the synthetic chemistry community. This review will focus on total and formal syntheses of exiguolide by Lee, Fuwa, Roulland, Scheidt, Reddy, Song, and Ishihara to illustrate advances in strategies for macrolide synthesis.

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Published online: 30th June, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14686
Efficient and Aqueous Synthesis of 3,4-Disubstituted Isoxazol-5(4H)-one Derivatives Using Piperazine under Green Conditions

Ziba Daroughezadeh and Hamzeh Kiyani*

*School of Chemistry, Damghan University, 36719-41167 Damghan, Iran

Abstract

The one-pot, three-component, as well as expeditious synthesis of 3,4-disubstitted isoxazol-5(4H)-ones has been attained from the heterocyclization of various aryl/heteroaryl aldehydes, active methylene compounds, and hydroxylamine hydrochloride in the presence of piperazine as the efficient, low-cost, commercially available, and eco-friendliness basic organocatalyst. This double secondary amine catalyst was found that catalyzed the synthesis of isoxazol-5(4H)-ones under green conditions. The additional features of the present catalyst include readily available starting materials, relatively low catalyst loading, using water as a green solvent, broad substrate scope, simplicity, good to excellent reaction yields, faster synthesis, and avoiding the hazardous organic solvents.

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Published online: 28th June, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14685
Regioselective Synthesis of Some Novel Phosphonopyrazole, Phosphonopyrimidine and Phosphonodiazepine Compounds Containing Coumarin Ring

Tarik E. Ali* and Mohammed A. Assiri

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt

Abstract

A convenient regioselective synthesis of some novel phosphonopyrazole, phosphonopyrimidine and phosphonodiazepine derivatives containing a coumarin ring, was designed. The methodology involves one-pot reaction of 3-(2-bromoacetyl)-2H-chromen-2-one (1) with dimethylformamide dimethyl acetal and diethyl phosphite to give diethyl [2-bromo-3-oxo-3-(2-oxo-2H-chromen-3-yl)prop-1-en-1-yl]phosphonate (2). The successful heterocyclization of substrate 2 with 1,2-, 1,3- and 1,4-diamine reagents afforded the target products in moderate to good yields.

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Published online: 24th June, 2022

Review | Regular issue | Prepress
DOI: 10.3987/REV-22-984
Gold-Catalyzed Skeletal Rearrangement Reactions of O-Propargylic and O-Homopropargylic Oximes

Itaru Nakamura* and Masahiro Terada

*Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan

Abstract

Au-catalyzed skeletal rearrangement reactions of O-propargylic oximes, which were derived from the condensation of N-propargyloxyamine with either formaldehyde or glyoxylate, afforded the corresponding 4-methylenated isoxazolines via C=N bond cleavage. The obtained isoxazolines underwent carbonyl–ene reactions, generating functionalized isoxazoles in good yields. Moreover, a sequence of Au-catalyzed reactions followed by a carbonyl–ene reaction of enantioenriched substrate produced isoxazoles having a chiral side chain, with excellent levels of chirality transfer. In contrast, the Au-catalyzed reactions of O-propargylic oximes bearing an electron-deficient aryl group on the oxime carbon proceeded via N–O bond cleavage, affording oxazines in good yields.

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18 data found. 1 - 18 listed