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Published online: 23rd September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14340
Stereoselective Synthesis of (Z)-3-Arylidene-2-oxindoles via a Palladium-Catalyzed Tandem Reaction

Sunhwa Park, Kye Jung Shin, and Jae Hong Seo*

*College of Pharmacy, The Catholic University of Korea, 43 Jinong-ro Wonmi-gu Bucheon, Gyeonggi-do, 14662, Korea

Abstract

A novel and efficient synthetic method for the stereoselective preparation of (Z)-3-arylideneoxindoles from simple propiolamide has been developed utilizing a palladium-catalyzed tandem reaction. Two Sonogashira and reductive Heck reactions were successfully combined under microwave irradiation. The E/Z stereoselectivity of the reaction was enhanced by solvent control.

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Published online: 18th September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14330
1-Hydroxyindoles: Production of Feruloylserotonin, an Alkalid of Safflower Seed, Novel Ring System Compound, 1,10-Diaza-9,20-dioxokabutanes, 2,2’-Bisindoles, and (dl)-3a, 3a’-Bispyrrolo[2,3-b]indoles

Mutsuko Tabata, Naoki Oshikiri, Masakazu Hasegawa, Keiichi Satoh, Yoshikazu Fukui, Yoshiyuki Nagahama, Harunobu Morikawa, Fumio Yamada, and Masanori Somei*

*Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan

Abstract

Methyl 1-hydroxyindole-3-acetate (1a) produced novel hexacyclic 8,17-bis(methoxycarbonylmethyl)-1,10-diaza-9,20-dioxakabutane (3) as a major product by the reaction with 85% formic acid, while its reaction with trifluoroacetic acid generated exclusively another 2,2’-bisindole dimer, 1-hydroxy-3,3’-di(methoxycarbonylmethyl)-2,2’-bisindole (4). Reaction of 1a with mineral acid such as HCl afforded nucleophile substituted 5-chloroindole derivative (6). Products and their distribution changed depending on the structure of 1-hydroxyindole. Species of acid, reaction conditions, side chain structure of 1-hydroxyindole at the 3-position are additional factors for governing the product formation. In the cases that the side chain has a C—C—N structure, nucleophilic substitution reaction occurred effectively, and was applied for the preparation of N-feruloylserotonin (46d), an alkaloid isolated from safflower seed. 1-Hydroxymelatonin (69), having a methoxy group on the benzenoid part, afforded (dl)-3a,3a’-bis(pyrrolo[2,3-b]indole) compound (72) by the treatment with 85% formic acid. Products’ structures are unequivocally determined by X-ray single crystallographic analyses.

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Published online: 18th September, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14335
Chromone Derivatives from the Twigs of Cassia Agnes and Their Anti-Rotavirus Activity

Guang-Hui Kong, Zhen-Yuan Xia, Fan Wu, Ya-Ning Zhu, Jing Li, Wei-Song Kong, Min Zhou, Guang-Yu Yang, Qiu-Fen Hu,* and Yu-Ping Wu*

*Yunnan Academy of Tobacco Agricultural Sciences, Kunming, Yunnan 650031, P. R. China

Abstract

Three new (1 - 3), together with four known chromone derivatives (4 - 7) were isolated from the twigs of Cassia agnes. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. Compounds 1 - 7 were evaluated for their anti-rotavirus activity. The results revealed that compounds 1 - 7 exhibited potent anti-rotavirus activity with TI valves in the range of 9.4 - 14.5, respectively.

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Published online: 15th September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14302
Synthesis of 4,7-Dibromobenzo[b]thiophene Derivatives via 2-(1-Adamantylsulfanyl)-1,4-dibromo-3-(ethynyl)benzenes and Their Reactions

Kozo Toyota,* Shinichi Mikami, Hiroki Tanaka, Shuhei Yoshida, Kazuma Iwai, Kenta Takahashi, Hiroki Kishi, Yota Kikuchi, Koya Saito, Homa Yamaguchi, and Hirotaka Mutoh

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

Abstract

Mild Corey-Fuchs reaction conditions using dimethyl sulfoxide - aqueous KOH solution at room temperature were applied to preparation of 2-(1-adamantylsulfanyl)-1,4-dibromo-3-(ethynyl)benzene. Various substituents were introduced to the terminal alkyne moiety of the (ethynyl)(sulfanyl)benzene, either by substitution reaction or by Sonogashira cross coupling. The alkynes thus obtained were converted to the corresponding 4,7-dibromobenzo[b]thiophene derivatives by the ‘silica gel-assisted cyclization method. Reactions of 4,7-dibromobenzo[b]thiophene and 2,4,7-tribromobenzo[b]thiophene were also investigated.

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Published online: 14th September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14316
Synthesis of Novel (Thiazol-5-yl)pyrazoles and Their Antimicrobial Evaluation

Sanjay U. Deshmukh,* Raghunath B. Toche,* Sushama J. Takate, Supriya P. Salve, and Ram W. Sabnis

*Department of Chemistry, KRT Arts, BH Commerce & AM Science College, Nashik 422002, India.

Abstract

A series of novel (thiazol-5-yl)pyrazoles were designed and synthesized. All the synthesized compounds were characterized by spectroscopic analysis and were evaluated for their antimicrobial activity in vitro against Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, Gram-negative bacteria, Salmonella abony and Escherichia coli and fungi, Aspergillus flavus and Fusarium oxysporum.

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Published online: 9th September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14317
Synthesis and Evaluation of β-Galactosidase-Targeting Spin-Label Probe: 5-O-β-D-Galactosyl-5-hydroxy-1,1,3,3-tetramethylisoindoline-2-oxyl

Koya Sugawara, Hiroyuki Konno, Tomohiro Ito, and Shingo Sato*

*Graduate School of Science and Engineering, Yamagata University, Jonan 4-3-16, Yonezawa-shi, Yamagata 992-8510, Japan

Abstract

In this study, 3-hydroxymethyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 5-hydroxy-1,1,3,3-tetramethylisoindoline-2-oxyl O-galactosides (PG, TG, and IG) were synthesized. Moreover, their reduction reactivity (RR) for ascorbic acid and hydrolysis reactivity (HR) for β-galactosidase were measured via electron paramagnetic resonance (EPR) spectroscopy and high-performance liquid chromatography (HPLC), respectively. The both rate constants for these two reactions were found to exhibit the following order: RR: TG > IG > PG, and HR: IG > PG > TG. Based on the results of the in vitro assay, IG was selected as the candidate for the bioassay. The bioassay of IG by HeLa cells (cancer cells) and PC12 cells (normal cells) indicated that after 20 min of IG addition, more nitroxide radicals were located in the cancer cells than in the normal cells, while their EPR intensity was low.

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Published online: 8th September, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-938
9,9'-Bi(Xanthene)-Type Hexaphenylethane Derivatives as Advanced Organic Electrochromic Systems

Takanori Suzuki,* Yusuke Ishigaki, Masaki Takata, Jun-ichi Nishida, and Takanori Fukushima

*Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

Abstract

9-Phenylxanthenyl radical can undergo facile C-C bond formation at C9-position when the two units of the radical are connected at C2'-positions to give stable intramolecular dimer (1), which is a clamped hexaphenylethane derivative with an elongated C-C bond. The newly formed bond in 1 can be cleaved easily upon two-electron oxidation to give bis(9-xanthenylium)-type dication (22+), from which the diradical is generated upon two-electron reduction. This review account describes the dynamic redox ("dyrex") pair of colorless 1 and yellow-orange 22+, which provides a versatile scaffold to develop multi-functional electrochromic systems. Both of 1 and 22+ are sterically challenged molecules and thus adopt characteristic skewed geometries. Electrochiroptical response was realized by suppressing the chiral inversion of helicity in 1 and axial chirality in 22+ whereas redox-induced fluorescence switching was attained by attaching the fluorophore whose emission is quenched by xanthenylium in 22+ but not by spiro(xanthene) unit in 1. By the molecular design that allows intramolecular chiral transmission, the spectral changes were also induced by the external stimuli (e.g. heat, pH) other than redox input, which made it possible to construct less well-explored multi-input-multi-output response systems. More advanced functions could be endowed, such as chiral redox memory or reversible O2-storage, by further modification of the prototype.

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Published online: 3rd September, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14327
Synthesis and Evaluation of Biological Properties of 2-(2-(Phenoxy)pyridin-3-yl)quinazolin-4(3H)-one Derivatives

Li-qiong Zhang, Jia-min Liu, Yi-yuan Gan, Li-hui Shao, Yi-hong Fu, Zhen-chao Wang,* and Gui-ping Ouyang*

*College of Pharmacy, Guizhou University, Huaxi St., Guiyang 550025, China

Abstract

A series of novel 2-(2-(phenoxy)pyridin-3-yl)quinazolin-4(3H)-one derivatives were designed, synthesized as antitumor agents. The antitumor activities of target compounds were evaluated and compared with positive drug Gefitinib employing standard MTT assay against A549 (human lung adenocarcinoma cell), PC-3 (prostate cancer cells), K562 (human chronic myeloid leukemia cells), HepG2 (human liver cancer cell) cancer cell lines in vitro. The pharmacological screening results revealed that many compounds exhibited moderate levels of antitumor activities against four cancer cell lines, especially 6-chloro-2-(2-(3,5-dimethylphenoxy)pyridin-3-yl)-3,8-dimethylquinazolin-4(3H)-one (z8) displayed promising activities against A549 (IC50 = 12.47±2.86 μM) than Gefitinib (IC50 = 17.37±6.01 μM). The mechanism and the apoptosis inducing effect of z8 against A549 cell line were studied. The results showed that z8 could inhibit migration and motility of cancer cells, induce cell apoptosis and exhibit the typical apoptotic morphology.

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Published online: 27th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14288
Design and Synthesis of Pentacycloundecane Cage Compound Containing Oxazole Moiety

Sambasivarao Kotha* and Subba Rao Cheekatla

*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India

Abstract

Here, we have established a new and simple synthetic approach to the pentacycloundecane containing cage oxazole unit in four steps. The synthesis begun with a cheap and readily available materials such as 2,5-dimethoxybenzaldehyde and endo-dicyclopentadiene. This approach relies on Van Leusen oxazole synthesis and [2+2] photocycloaddition as key steps. To the best of our knowledge, this is the first example of Cookson’s dione containing oxazole ring system. Some of these oxazole motifs are useful in bioorganic chemistry and our results are likely to draw the attention of medicinal chemists

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Published online: 26th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14321
Facile Preparation of 5-Alkyl-1-aryltetrazoles with Arenes, Acyl Chlorides, Hydroxylamine, and Diphenylphosphoryl Azide

Kaho Shibasaki and Hideo Togo*

*Graduate School of Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Abstract

Successive treatment of arenes with acyl chlorides and AlCl3, the addition of water and removal of solvent, the reaction with NH2OH•HCl and K2CO3, and the reaction with diphenylphosphoryl azide and DBU under warming conditions gave the corresponding 5-alkyl-1-aryltetrazoles efficiently in good to moderate yields. The present method is one-pot transformation of arenes into 5-alkyl-1-aryltetrazoles using the Friedel-Crafts acylation and the Beckmann rearrangement under transition-metal-free conditions.

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Published online: 25th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14333
Synthesis and Reactivity of Dimethoxy Activated Benzothiazoles

Mahiuddin Alamgir, Hao Jiang, Mohan Bhadbhade, Naresh Kumar, and David StC. Black*

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

Abstract

A range of 2-substituted-5,7-dimethoxybenzothiazoles and 2-substituted-4,6-dimethoxybenzothiazoles have been synthesized by oxidative cyclization of the corresponding thioamides. These activated benzothiazoles display nucleophilic reactivity at C4 and C7 respectively and undergo formylation, acetylation and related reactions. Some 5,7-dimethoxybenzothiazoles with functionalization in a 2-aryl substituent are also reported as potential precursors for so far unsuccessful formation of macrocycles containing two benzothiazoles and two benzimidazoles.

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Published online: 21st August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14298
Synthesis and Antibacterial Survey of Some New Pyridine-Based Heterocycles

Ebrahim Abdel-Galil, Moged A. Berghot, Alshimaa I. Zaki, and Ehab Abdel-Latif*

*Department of Chemistry, Faculty of Science, Mansoura University, Mansoura, Egypt

Abstract

Treatment of ethyl 2-((3-cyano-4,6-dimethylpyridin-2-yl)thio)acetate (4) with hydrazine hydrate furnished 2-((3-cyano-4,6-dimethylpyridin-2-yl)thio)-acetohydrazide (5) which underwent condensation with five benzaldehydes to afford the corresponding N'-arylidene-2-((3-cyano-4,6-dimethylpyridin-2-yl)thio)-acetohydrazides 6a-e. The reaction of hydrazide 5 with ethyl acetoacetate yielded the expected 2-((2-(3-methyl-5-oxo-pyrazolyl)-2-oxoethyl)thio)nicotinonitrile derivative 7 which diazo-coupled with different diazonium chlorides to furnish the corresponding 2-(4-(2-arylhydrazono)pyrazolyl)-2-oxoethyl)thio)nicotinonitriles 8a-c. In addition, the nucleophilic substitution of chlorine from 2-chloroacetamide derivative 16 by various types of nucleophiles (salicylaldehyde, ethyl thioglycolate, 2-mercaptobenzoxazole, ammonium thiocyanate and/or malononitrile) was investigated. In general, all synthesized pyridine scaffolds revealed better activity against the Gram-positive bacterium (Bacillus subtilis) rather than the Gram-negative bacterium (Escherichia coli).

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Published online: 20th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14300
An Efficient Synthesis of Some New Coumarin Hybrids Endowed with Expected Biological Activity

Mohamed A. Raslan,* Noura Sh. Hagaggi, Kamal M. Dawood, Hany A. Abdel Atty, and Ayman Nafady

*Department of Chemistry, Faculty of Science, Aswan University, Aswan 81528, Egypt

Abstract

Reactions of 5-bromo-2-hydroxybenzaldehyde with cyanoacetic acid hydrazide derivatives in refluxing ethanol afforded some new chromene-based polyfunctionally substituted heteroaromatics. The antimicrobial activity of some of the obtained products was evaluated. The structures of the newly synthesized compounds were elucidated based on their elemental analyses and spectral data.

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Published online: 20th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14305
Identification and Characterization of Chlorine-Containing Briaranes from a Cultured Octocoral Briareum excavatum (Briareidae)

Yi-Lin Zhang, Liang-Mou Kuo, Lo-Yun Chen, Gene-Hsiang Lee, Bo-Rong Peng, You-Ying Chen, Yu-Hsin Chen, Tsong-Long Hwang,* Jyh-Horng Sheu,* and Ping-Jyun Sung*

*Department of Planning and Research, National Museum of Marine Biology and Aquarium, 2 Houwan Road, Checheng, Pingtung, Taiwan 944, Taiwan

Abstract

Six chlorine-containing briaranes, including two new compounds, briarenols M (1) and N (2), as well as four known metabolites solenolide E (3), briarenolide R (4), excavatolide A (5), and briaexcavatolide F (6), have been isolated from a cultured octocoral identified as Briareum excavatum. The structures of 1 and 2 were established by spectroscopic methods and the absolute configurations of 5 and 6 were confirmed by single-crystal X-ray diffraction analysis. These compounds were subjected into the inhibitory effects on fMLF/CB stimulated superoxide anion generation and elastase release in human neutrophils.

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Published online: 20th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14306
Synthesis and Reactions of 3,8-Diphenyl-5-(4-methoxyphenyl)pyrrolo[1,2-c][1,3]thiazolo[3,2-a]pyrimidine-6-carbohydrazide

Kamelia M. El-mahdy and Azza M. El-kazak*

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11757, Cairo, Egypt

Abstract

The reaction of 2-mercaptopyrimidine 1 with phenacyl bromide gave pyrrolothiazolopyrimidine 2, which underwent hydrazinolysis to produce the novel pyrrolo[1,2-c][1,3]thiazolo[3,2-a]pyrimidine-6-carbohydrazide 3. Compound 3 used as a key intermediate for the synthesis of poly fused and isolated systems bearing pyrrolo[1,2-c][1,3]thiazolo[3,2-a]pyrimidine moiety via its reactions with some heterocyclization reagents. Structures of the newly synthesized compounds were established by elemental analysis and spectral data (IR, 1H NMR, Mass spectra and 13C NMR). The prepared compounds would be expected to have biological activities.

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Published online: 20th August, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-937
Pyrrolotetrazoles and Ring-Fused Derivatives

Dietrich Moderhack*

*Institute of Medicinal and Pharmaceutical Chemistry, Technical University, Braunschweig, Beethovenstrasse 55, D-38106, Germany

Abstract

The preparative chemistry of seven types of pyrrolotetrazoles (formally: pyrrolo[1,2-d]tetrazoles) AG including five ring-fused derivatives such as B', B'', C', C'', and E' is surveyed in this article. Theoretical work on annular tautomerism and pyrrolotetrazole–azidopyrrole isomerism is dealt with complementarily.

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Published online: 20th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14315
Amphirionins-3 and -6, New Polyketides from the Cultured Marine Dinoflagellate Amphidinium Species

Masashi Tsuda,* Ryui Makihara, Mika Minamida, Masayuki Tsuda, Mai Akakabe, Keiko Kumagai, Eri Fukushi, Jun Kawabata, and Takeyuki Suzuki

*Center for Advanced Marine Core Research , Kochi University, Nankoku, Kochi 783-8502, Japan

Abstract

Amphirionins-3 (1) and -6 (2) have been isolated from the marine dinoflagellate Amphidinium species. The structures were elucidated by detail analyses of the spectroscopic data, and chemical conversions. Compounds 1 and 2 exhibited moderate cytotoxic activity against human cervix adenocarcinoma HeLa cells.

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Published online: 20th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14324
Efficient Synthesis and Anticancer Activities of Some Novel Functionalized (4-Oxo-4H-chromen-3-yl)-2-selenoxo-1,2-dihydropyrimidines

Tarik E. Ali,* Mohammed A. Assiri, Mamdouh M. Ali, Abeer E. M. Ali, Ibrahim S. Yahia, and Heba. Y. Zahran

*Department of Chemistry, Faculty of Science, King Khalid University, Abha, Saudi Arabia

Abstract

Some novel functionalized 2-selenoxo-1,2-dihydropyrimidines bearing a chromone ring 2a-h were synthesized in excellent yields via a simple one-pot reaction. The simple method depended on one-pot three-component the reaction of 3-formylchromone (1) and selenourea with some active methylene compounds in the presence of sodium benzoate as a basic catalyst in a mixture of ethanol and water. The reactions were completed in 1.5–2.5 h in 88-94% yields. Structures of the synthesized compounds were based on elemental analysis, IR, 1H- and 13C-NMR and mass spectrometry. The anticancer properties of the synthesized compounds were evaluated against five cancer cell lines. Compounds 2a-d displayed the most potent anticancer activities against A549, MCF-7 and HepG2 cell lines in comparison with doxorubicin as the standard drug.

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Published online: 19th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14325
Synthesis of Some Novel Antimicrobial and Antioxidant Agents of Functionalized Pyrazolo[4',3':5,6]pyrano[3,2-d]- [1,2]azaphospholes and Pyrazolo[4',3':5,6]pyrano[2,3-d][1,3,2]diazaphosphinines

Noha M. Hassanin,* Tarik E. Ali, Hafez M. El-Shaaer, Somaia M. Abdel-Kariem, Somaya M. El-Edfawy, and Wafaa R. Abdel-Monem

*Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11757, Cairo, Egypt

Abstract

We have demonstrated facile synthetic approach for some novel functionalized pyrazolo[4',3':5,6]pyrano[3,2-d]-[1,2]azaphospholes and pyrazolo[4',3':5,6]pyrano[2,3-d][1,3,2]diazaphosphinines via treatment of 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile with some phosphorus halides. The structure of the products was characterized by elemental analysis and spectral tools. The antimicrobial and antioxidant activities of the products were also evaluated.

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Published online: 18th August, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-936
An Overview of Quantitative and Qualitative Approaches on the Synthesis of Heterocyclic Kojic Acid Scaffolds through the Multi-Component Reactions

Fatemeh Mohajer and Ghodsi Mohammadi Ziarani*

*Department of Chemistry, Alzahra University, Vanak Square, 1993893973, Tehran, Iran

Abstract

Multi-component reactions as powerful synthetic methods were developed to provide efficient complex scaffolds, including kojic acid, through the one-pot one-step fashion. This review highlights the progress of multicomponent reactions covering kojic acid under different conditions through, short reaction time, higher yields, and environmental friendliness via producing various molecules. The aim of this paper is to review the literature from 2015 to 2020 via quantitative and qualitative approaches.

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Published online: 13th August, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-933
Recent Development of Stereoselective Glycosylation Reactions

Shino Manabe*

*Laboratory of Functional Molecule Chemistry, Pharmaceutical Department and Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo, 142-8501, Japan

Abstract

Carbohydrates are the most abundant class among biological molecules. Advances in glycobiology have revealed the vital roles played by glycosides and glycoconjugates in biological events. In this context, access to homogenous oligosaccharides and glycoconjugates is critical for various biological investigations. Glycosylation is the cornerstone of glycoside synthesis, and during glycosylation, the control of stereoselectivity at the anomeric position is highly important. In this review, recent progresses in 1,2-cis-glycosylation reactions are summarized, with a focus on the influence of the protecting groups on the conformations of the glycosyl donors, role of reaction mixture additives, and synthetic utility of endocyclic cleavage of glycoside. Development of robust glycosylation reaction will contribute to biologically active oligosaccharide synthesis.

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Published online: 13th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14329
Four-Component Domino Reaction for the Synthesis of Novel 8-Methyl-9-substituted-2,10-diaryl-2,3-dihydro-10H-pyrano[3,2-e][1,2,4,3]triazaphospholo[1,5-c]pyrimidines

Dina A. Bakhotmah and Tarik E. Ali*

*Department of Chemistry, Faculty of Science, King Khalid University, Abha, Saudi Arabia

Abstract

A novel four-component domino reaction for the synthesis of 8-methyl-9-substituted-2,10-diaryl-2,3-dihydro-10H-pyrano[3,2-e]-[1,2,4,3]triazaphospholo[1,5-c]pyrimidines has been established. The reaction was performed in THF using readily available 5-substituted-2-amino-6-methyl-4-phenyl-4H-pyran-3-carbonitrile, dimethyl-formamide dimethyl acetal, hydrazine hydrate and aryldichlorophosphine. The simple and efficient one-pot four-component approach, catalyst free and mild reaction conditions made the present methodology a good synthetic procedure.

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Published online: 12th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14308
Some New C3- and Cs-Symmetrical Trialkylamino-substituted 1,3,5-Triazines and Their Biological Evaluation

Shunsuke Shimomura, Yusuke Inoue, Yuki Kawano, Yuka Fujita, Kanae Yamada, Yumemi Matsumoto, Kazumi Yokomizo, Jian-Rong Zhou, Kaori Ota, Nobuko Mibu, Makoto Furutachi, and Kunihiro Sumoto*

*Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan

Abstract

We report the preparation of some new additionally synthesized symmetrical 1,3,5-triazines (TAZ) and the results of biological evaluation of their anti-herpes simplex virus type 1 (anti-HSV-1) activity and cytotoxic activity against Vero cells. All of the new trisubstituted TAZ derivatives 3a-3e showed considerable levels of anti-HSV-1 activity (EC50 = 4.4 ~ 30.3 μM). Among the tested compounds, two compounds (3c-2 and 3d) that have three 3,4-methylenedioxyphenylalkylamino groups showed low levels of cytotoxicity (CC50 > 200 μM) against Vero cells. On the other hand, the C3-symmetrical TAZ derivatives 3a-2, 3b-2 and 3e showed considerably high levels of cytotoxicity (CC50 = 8.91 ~ 15.2 μM). The structure-activity relationships for anti-HSV-1 activity and cytotoxicity of synthesized single-drug type 2,4,6-trisubstituted TAZ derivatives are also discussed.

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Published online: 12th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14314
A One-Pot Four-Component Procedure for the Synthesis of Dispiro[tetrahydroquinoline-bis(2,2-dimethyl-1,3-dioxane-4,6-dione)] Derivatives

Zhaohui Xu,* Yexuan Tang, Qiang Xiao, and Chuanwen Liao*

*Department of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, P.R. China.

Abstract

A simple and efficient procedure for the diastereoselective synthesis of dispiro[tetrahydroquinoline-bis(2,2-dimethyl-1,3-dioxane-4,6-dione)] derivatives through one-pot four-component reaction of aromatic aldehydes, 2,2-dimethyl-1,3-dioxane-4,6-dione, arylamines and acetone in the presence of potassium dihydrogen phosphate (KDP) is described. The procedure involves initial Knoevenagel reaction, followed by Diels-Alder, Michael additon and intramolecular reactions. The main advantages of the protocol are the high isolated yields, broad substrate scope, mild conditions, and easy operation.

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Published online: 7th August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14320
Ukixanthomycin A: a Hexacyclic Xanthone from the Mudflat-Derived Actinomycete Streptomyces sp.

Yuhei Koyanagi, Teppei Kawahara, Yuki Hitora, and Sachiko Tsukamoto*

*Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan

Abstract

A new hexacyclic xanthone, ukixanthomycin A (1), was isolated from the mudflat-derived Streptomyces sp. HGMA004 by screening based on chemical analysis by UPLC-HRMS with our in-house actinomycete extract library. The structure of 1 was elucidated by spectral analyses and quantum chemical calculations. Compound 1 showed weak antifungal activity against Candida albicans.

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Published online: 4th August, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14312
Design and Synthesis of 4'-Cyano Dideoxy Isonucleosides and Their Activity against HIV-1 and HBV

Kengo Onitsuka, Kakeru Yamaguchi, Ryoh Tokuda, Nobuyo Higashi-Kuwata, Shunsuke Kuwahara, Hiroki Kumamoto, Kenji Maeda, Kazuhiro Haraguchi, Hiroaki Mitsuya, and Shuhei Imoto*

*Faculty of Pharmaceutical Sciences, Sojo University, 4-22-1, Ikeda, Kumamoto-shi, 860-0082, Japan

Abstract

Nucleoside reverse-transcriptase inhibitors are major antiviral agents against HIV-1 and HBV. Here, we describe the synthesis of a novel 4'-cyano dideoxy isonucleoside 6 and its phosphoramidate prodrug 7. Intermediate 16 is a promising precursor for the preparation of isonucleosides bearing substituents at the 4' position with various nucleobases. In addition, 6 and 7 were evaluated for their antiviral properties against HIV-1 and HBV. Compound 7 displayed weak anti-HIV activity (EC50 = 61.4 μM) and had no observed cytotoxicity in two different cell systems.

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Published online: 3rd August, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14309
Change in the Fluorescence of 1,1′-Diaryl-2,2′-biimidazoles upon the Addition of Acid

Shoji Matsumoto,* Seigi Tachibana, and Motohiro Akazome

*Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Abstract

The optical properties of a series of 1,1′-diaryl-2,2′-biimidazoles were examined. Different transitions were observed in their fluorescence spectra upon changing the electronic properties of the phenyl ring at the C1 and C1′ positions. The presence of a formyl group on the phenyl ring results in fluorescence via a CT transition with a solvent effect. A bathochromic change was observed when HCl was added to a solution of compound bearing a methoxy group in CH2Cl2, whereas a hypsochromic change was observed in compound bearing a formyl group. These observations were attributed to the protonation, which causes a characteristic change in their biimidazole moieties.

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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: 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: 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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