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14 data found. 1 - 14 listed

Published online: 3rd July, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14276
Efficient Synthesis of 2-Functionalized Benzoxazoles Catalyzed by Copper Iodide

Han Cao,* Xue-jing Liu,* Fu-Sheng Bie, Peng Yan, Jie Ma, Yi-Jun Shi, and Ying Han

*Engineering and Technology Research Institute of Lunan Coal Chemical,, Zaozhuang University, 1 Beian Road, China

Abstract

We reported an efficient synthesis of 2-functionalized benzoxazoles in mild condition and excellent yields. The synthetic process includes two steps. The step one contains a reaction of pendent halide formamidine derivatives and 2- aryloxyacetyl chloride generating highly selective (Z)-N-(2-halophenyl)-3-(dime- thyllamino)-2-aryloxyacrylamides, and the step two undergoes copper iodide catalyzed intramolecular C-O bond formation to yield title compounds. This strategy is not only providing newly discovered key intermediates 6a-l which contain multiple functional groups on 2-position (as building blocks), but also expanded the scope of methodologies for making diverse benzoxazoles with multiple functional groups.

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Published online: 3rd July, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-934
Aryne-Mediated Synthesis of Oxygen Heterocycles and Application to Cysteine-Selective Trapping

Hideto Miyabe*

*Laboratory for Medicinal Chemistry, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe City, 650-8530, Japan

Abstract

The use of arynes as the highly reactive intermediates in organic synthesis has attracted substantial attention. Particularly, the introduction of ortho-(trimethylsilyl)aryl triflates as easily activatable aryne precursors led to growing activity in this field. Most reactions using these aryne precursors proceed through the addition of nucleophiles to arynes and the subsequent trapping with electrophiles to give the multisubstituted arenes with structural diversity and complexity. Based on our studies, this review highlights the insertion of arynes, generated from ortho-(trimethylsilyl)aryl triflates, into C=O π-bond of formamides. Initially, the representative examples for formal [2+2] cycloaddition of arynes with the carbon–heteroatom double bond or the heteroatom–heteroatom double bond are shown. Next, the studies on the insertion of arynes into the N−C and C=O bonds of amide group including our three-component coupling reaction leading to oxygen heterocycles are summarized. The SN2’ reaction of tricyclic oxygen heterocycles, obtained by three-component coupling reaction, was studied by using carbon and sulfur nucleophiles. The SN2’ reaction was expanded to four-component coupling reaction. Finally, the application of tricyclic oxygen heterocycles to cysteine-selective trapping is described.

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Published online: 3rd July, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14296
Three New Benzazepine Alkaloids from Thalictrum Cirrhosum and Their Anti-Rotavirus Activity

Qiu-Fen Hu, Dian Luo, Na Lv, Ya-Ning Zhu, Lu Liu, Fan Wu, Dong Miao, Wei-Guang Wang, Qian Gao, Min Zhou,* and Guang-Yu Yang*

*Technical center, China Tobacco Yunnan Industrial Co., Ltd., Keyi Road 41#, China

Abstract

Three new benzazepine alkaloids, cirrhobenzazepines A-C (1-3), together with four known alkaloids (4-7) were isolated from the whole plants of Thalictrum cirrhosum. Their structures were elucidated by spectroscopic methods, including extensive 1H, 13C, and 2D-NMR techniques. Compounds 1-7 were tested for their anti-rotavirus activity. The results revealed that compounds 1-7 exhibited potent anti-rotavirus activity with TI valves in the range of 11.9-18.2, respectively.

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Published online: 1st July, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14280
Reactivity of 4,6-Dimethoxy Activated Benzimidazoles

Mahiuddin Alamgir, Glenn C. Condie, Vesna Martinovic, Joanne Wood, Mohan Bhadbhade, Naresh Kumar, and David StC. Black*

*School of Chemistry, The University of New South Wales, Sydney 2052, Australia

Abstract

4,6-Dimethoxy-2-substituted-benzimidazoles undergo formylation, acylation, nitration and bromination at C7. The 7-carbaldehydes can be reduced to the corresponding hydroxymethyl compounds. Benzimidazole-2-carbaldehydes can be prepared by oxidation of 2-methyl- and 2-styryl-benzimidazoles. N-Methylation and N-allylation have also been investigated and lead to isomeric mixtures of 4,6- and 5,7-dimethoxybenzimidazoles. In general the nucleophilic capacity of the activated benzimidazoles is weaker than that of the related activated indoles, but still provides synthetic routes to a range of new heterocyclic structures.

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Published online: 30th June, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14273
Chemical Transformations with 4,9-Dimethoxy-5-Oxo-5h- Furo[3,2-G]Chromene-6-Carbonitrile: Construction and Antimicrobial Evaluation of The Novel Heteroannulated Furochromenopyridines

Magdy A. Ibrahim,* Sami A. Al-Harbi, and Esam S. Allehyani

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy, Cairo 11711, Egypt

Abstract

The chemical reactivity of 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]- chromene-6-carbonitrile (1) was studied towards a variety of active methylene nitriles namely; malononitrile, cyanoacetamide, N-phenylcyanoacetamide, (phenylthio)acetonitrile, ethyl cyanoacetate and benzothiazol-2-ylacetonitrile producing the novel annulated furo[3’,2’:6,7]chromeno[2,3-b]pyridines. Reactions of carbonitrile 1 with malononitrile dimer, cyanoacetohydrazide and 1H-benzimidazol-2-ylacetonitrile showed different behavior giving the novel angular heteroannulated furochromenes 10, 11 and 13, respectively. A series of novel furo[3’’,2’’:6’,7’]chromeno[3’,2’:5,6]pyrido[2,3-d]pyrimidines were also synthesized. The proposed mechanisms for the different synthetic pathways were also discussed. The prepared compounds were screened in vitro for their antimicrobial activity and some of them showed notable activity against the tested microorganisms. Structures of the synthesized products were confirmed based on their analytical and spectral data.

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Published online: 18th June, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14282
Synthesis and Biological Evaluation of New Curcumin Analogs Inhibiting Osteoclastogenesis

Aoi Sugawara, Toshika Ohashi, Satoshi Ogawa, Naomi Goto, Mayumi Nakanishi-Matsui, Satoru Tamura, and Tomikazu Kawano*

*School of Pharmacy, Iwate Medical University, 1-1-1 Idaidori, Yahaba , Iwate, Japan

Abstract

A series of curcumin analogs (1-3) were newly designed and synthesized for the development of therapeutic agents for osteoporosis. Among the synthesized compounds, 2,5-substituted conjugated thiophene derivative (1a) and the corresponding pyrazine derivative (1c) were shown to be potential leads for the development of anti-osteoclastogenesis agent.

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Published online: 11th June, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-930
Synthesis of Nitrogen Heterocycles through Cyanative Cyclization and Cycloaddition Reactions under Transition Metal Catalysis

Shigeru Arai* and Atsushi Nishida

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, Japan

Abstract

Synthesis of cyano-functionalized nitrogen heterocycles under palladium, nickel, and cobalt catalysis is described. These transformations include the activation of C-C multiple bonds to give the functionalized pyrrolidines and their related compounds. The palladium-catalyzed reactions promote nucleophilic cyanation to non-activated terminal alkynes. Nickel catalysis enables to install H and CN functionalities into allenes with regio- and stereoselective manner. In the case of cobalt-catalyzed hydrocyanation, hydroacylation and hydroarylation, simple olefins as well as enamines are suitable substrates to construct highly functionalized hetero- and carbocycles. The applications of the above methodologies for the synthesis of alkaloids and related compounds are also described.

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Published online: 9th June, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14278
Synthesis of Dimethoxy Activated Benzimidazoles and Bisbenzimidazoles

Mahiuddin Alamgir, Glenn C. Condie, Vesna Martinovic, Joanne Wood, Hayat Sholihin, Paul K. Bowyer, Naresh Kumar, and David StC. Black*

*School of Chemistry, The University of New South Wales, Sydney 2052, Australia

Abstract

A range of 2-substituted-4,6-dimethoxy activated benzimidazoles and 2,2'-bisbenzimidazoles have been synthesized from 2-aminoanilide derivatives under acidic conditions. The starting materials were prepared either by acylation from 3,5-dimethoxyaniline followed by nitration, or by acylation from 3,5-dimethoxy-2-nitroaniline. The 2-nitroanilides were then reduced by palladium catalyzed reaction with hydrazine and subsequent acid catalyzed cyclization giving the corresponding 4,6-dimethoxybenzimidazoles and 4,6-dimethoxy-2,2'-bisbenzimidazoles. In addition, 2-phenyl-4,5,6-trimethoxybenzimidazole has been synthesized using a similar procedure.

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Published online: 5th June, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14266
Preparation and Acetylcholinesterase Inhibitory Activities of Pyridine-Based 1,3,4-Oxadiazole Derivatives

Xiang Yu,* Wude Yang, Ling Huang, Xingji Zhou, and Yafang Chen*

*Department of Pharmacy, Guizhou University of Traditional Chinese Medicne, , China

Abstract

Fourteen pyridine-based 1,3,4-oxadiazole derivatives were synthesized from pyridine-2-carboxaldehyde via iodine-mediated oxidative cyclisation with substituted hydrazide by using the impregnation method. Their structures were confirmed by melting point, 1H NMR, 13C NMR and HRMS. Preliminary bioassay of these derivatives' activities inhibiting acetylcholinesterase (AChE) was also evaluated in vitro at the concentration of 1 μmol/mL. The result showed that compounds 4c, 4j and 4k had moderate inhibitory activities with 52%, 59% and 59%, respectively. The preliminary structure-activity relationships revealed that the introduction of pyridine ring could enhance the activity. Molecular docking study demonstrated that compound 4k possessed an optimal docking pose with interactions at the middle of the catalytic active site (CAS) and peripheral anionic site (PAS) of AChE.

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Published online: 5th June, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14268
When Hydrazonoyl Chlorides Meet Terminal Alkynes: Regioselective Copper (I)-Catalysed "Click" Sequential Reactions to 5-Substituted Pyrazoles

Giorgio Molteni*

*Department of Chemistry, University of Milano, Via Golgi 19, 20133 Milano, Italy

Abstract

In the presence of catalytic amounts of copper(I) salts, terminal alkynes underwent the formation of copper(I) acetylides that enabled their nucleophilic addition onto hydrazonoyl chlorides followed by spontaneous cyclisation of the resulting alkynylhydrazone intermediate. This sequential reaction sequence was exploited as a facile and regioselective synthesis of 1,3,5-substituted pyrazoles. A catalytic cycle has been proposed accounting for the observed results.

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Published online: 22nd May, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-929
Chemical Syntheses and Biological Studies of Agelastatin A, A Bioactive Marine Heterocycle Gifted from Nature

Takehiko Yoshimitsu*

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

Abstract

Agelastatin A, an alkaloid originally isolated from the marine sponge Agelas dendromorpha, has long been an attractive target of chemical synthesis due to its significant biological activity and unique chemical structure. The synthetic approaches to the agelastatin alkaloid have demonstrated the advances of new methodologies and strategies for accessing a highly functionalized polycyclic nitrogen heterocycle. The present article reviews synthetic endeavors on agelastatin A that have been made by various synthetic chemists as well as biological studies on the natural product and its analogues aimed at the development of medicinal resources.

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Published online: 8th May, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-19-924
New and Practical Applications of Functionalized Cyclotriphosphazene Core-Based Materials

Manabu Kuroboshi* and Hideo Tanaka

*Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka 3-1-1, Kita-ku, Okayama, 700-7530, Japan.

Abstract

Hexachlorocyclotriphosphazene (HCCP) is a very old compound, and used as a starring material of a variety of cyclotriphosphazene derivatives. Some of them have unique properties, and have been used in not only frame retardants but also functional materials and biomaterials. To develop cyclotriphosphazene derivatives having a desired function, numbers of substituents, regio-, and stereochemistry should be controlled in the reaction between HCCP and nucleophiles. In this review, selectivity in the reaction between HCCP and nucleophiles as well as application of the cyclotriphosphazene derivatives are summarized.

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Published online: 27th April, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-928
Recent Advances in the Total Synthesis of Clavilactones

Akihiro Ogura and Ken-ichi Takao*

*Department of Applied Chemistry, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, Japan

Abstract

Clavilactones are meroterpenoids containing a 10-membered carbocycle fused to an α,β-epoxy-γ-lactone and a hydroquinone or benzoquinone. This review describes the total synthesis of clavilactones achieved by four research groups, focusing on their innovative synthetic strategies.

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Published online: 9th April, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-927
5,15-Diheteroporphyrins Synthesized from α,α'-Dihalodipyrrin as a Key Building Block

Soji Shimizu*

*Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

Abstract

A facile synthesis of meso-aryl-substituted α,α'-dihalodipyrrins and their use as starting materials in the porphyrin synthesis have enabled creation of various porphyrin analogues containing heteroatoms at two opposite meso-positions, namely 5,15-positions. Incorporation of lone pair electrons into the 18π-electron aromatic conjugated system of porphyrin allows the system to attain antiaromaticity with unique optical and electrochemical properties. This review summarizes the recent development in the chemistry of 5,15-diheteroporphyrins synthesized from meso-aryl-substituted α,α'-dihalodipyrrins.

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14 data found. 1 - 14 listed