Regular & Special Issues

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Published online: 20th April, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14446
Recyclable Heterogeneous Nanocrystal Promoted Cascade Reaction in Water: An Access to Green Synthesis of Highly Functionalized 4H-pyrans Containing Phosphonate Motif

Yong-Hong Cai, Ya-Sa Xie, Ran Li, Ming-Mei Fan, Jing-Jing Li, Chuan-Bao Zhang,* and Jin-Fang Yuan*

*College of Chemistry and Chemical Engineering, Henan University, Kaifeng, 475004, China.


A green and environmentally friendly cascade reaction of diethyl (2-phenylacetyl)phosphonate with benzylidenemalononitrile promoted by Zr-Ce-SBA-15-NH2 in water was developed, and a wide range of highly functionalized 4H-pyrans containing phosphonate motif were obtained in up to 89% yield. Moreover, SBA-15-NH2 also showed good catalytic activity for this transformation in acetonitrile.

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Published online: 15th April, 2021

Review | Regular issue | Prepress
DOI: 10.3987/REV-21-958
Recent Advances in 1,2,4-Triazole Ring Construction via Cycloaddition Reactions

Nataliya Korol,* Mikhailo Slivka, and Oksana Holovko-Kamoshenkova

*Organic synthesis laboratory, Faculty of Chemistry, Uzhhorod National University, Uzhhorod 88000, Ukraine


The sources, describing cycloaddition reactions that lead to obtaining of substituted 1,2,4-triazoles and their fused derivatives were reviewed. The review article covers the literature data published in the period 2011-2021. Synthetic particularities of cycloaddition products, the optimization of reaction conditions, factors that influence on the direction of the reaction are reasonably mentioned. Cycloaddition reactions are presented as convenient method for obtaining of as functional 1,2,4-triazoles, as well as their fused derivatives.


Published online: 14th April, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14460
Metal-Free SP3 C-H Bond Oxidation and Functionalization of α-Bromoketones to Quinoxalinone, Benzoxazinone, and Benzothiazinone Heterocyclic Compounds

Tianlong Wei, Haiying Tian, Fang Guo,* Hongxue Qi, and Xiuling Chen*

*School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, China


A series of heterocyclic compounds (benzothiazinones, benzoxazinones and quinoxalinones) were efficiently synthesized in excellent yields via α-bromoketones with o-substituted aniline (2-aminothiophenol, aryl-1,2-diamines and 2-aminophenol). This protocol accomplishes sp3 C-H bond oxidation and functionalization in one-pot without any metal catalyst.

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Published online: 12th April, 2021

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-950
Iodine-Containing 4,7-Dihalobenzo[b]thiophene Building Blocks and Related Iodobenzo[b]thiophenes: Promising Molecular Scaffolds for Bio-Inspired Molecular Architecture

Kozo Toyota* and Shinichi Mikami

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


This review describes preparations and reactions of 4,7-dihalobenzo[b]thiophenes bearing iodine atom(s). A short survey of typical preparative methods for iodobenzo[b]thiophenes and relatively simple benzo[b]thiophenes is included. Reactions of the iodine-containing 4,7-dihalobenzo[b]thiophenes are shown and their application to α helix-inspired artificial molecular architecture is referred.


Published online: 12th April, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14459
A One-Pot Approach to Construct 3-(2-Methoxypyridin-3-yl)-4H-chromen-4-ones via Meinwald Rearrangement/Intramolecular Demethylation Annulation of Epoxides

Min-Qi Hu, Ying Zhang, Kai-Li Dai, Li-Fang Yu, Ting Liu, Jie Tang, and Fan Yang*

*Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, PR China


A convenient and practical approach for construction of 3-(2-methoxypyridin-3-yl)-4H-chromen-4-ones has been successfully developed by a one-pot Meinwald rearrangement/intramolecular demethylation annulation reaction sequence with easily accessible epoxides as the starting material. The synthetic protocol is of excellent functional group compatibility under mild reaction conditions, and 3-(2-methoxypyridin-3-yl)-4H-chromen-4-ones were obtained in high yields. Moreover, further derivation successfully furnished more complicated derivatives by Suzuki-Miyaura cross-coupling reaction which may provide a promising potential application in exploring biological activity of 3-aryl-4H-chromen-4-ones.

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Published online: 12th April, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14461
Three-Component Reaction of Arynes, Quinolines, and Chloroform: Two-Step Synthesis of 2-Quinolinones from Quinolines

Kentaro Okuma,* Shiho Inomata, Yuxuan Qu, and Noriyoshi Nagahora

*Faculty of Science, Fukuoka University, Jonan-ku, Fukuoka 814-0180, Japan


Reaction of quinoline with benzyne prepared from benzenediazonium 2-carboxlate and chloroform gave 1-phenyl-2-trichloromethyl-1,2- dihydroquinoline in 79% yield. Basic hydrolysis of dihydroquinoline by KOH resulted in the formation of 2-quinolinone in 85% yield.

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Published online: 6th April, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14448
Synthesis and Biological Activities of Some New Phosphorus Compounds Containing Pyranopyrazole Moiety

Tarik E. Ali,* Mohammed A. Assiri, Hafez M. El-Shaaer, Somaia M. Abed-Kariem, Wafaa R. Abdel-Monem, Somaya M. El-Edfawy, Noha M. Hassanin, Ali A. Shati, Mohammad Y. Alfaifi, and Serag Eldin I. Elbehairi

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


A simple method for construction of functionalized pyranopyrazoles containing phosphoramide and phosphonate groups via one-pot reaction was achieved. The methodology depended on the reaction of 6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (3) with triethyl phosphite and hexaethylphosphoramide and so with diethyl phosphite in the presence of chloroacetyl chloride or carbon disulfide. The products were screened for their antimicrobial, antioxidant and antiproliferative properties. Compound 7 displayed promising antimicrobial and antioxidative properties. Also, compound 8 showed potent cytotoxic effects against MCF-7, HepG-2 and HCT-116 cancer cells with IC50 values in range 5.3 ± 0.9 to 7.5 ± 0.6 μg/mL. Acridine orange and ethidium bromide were used for the detection of viable, apoptotic, and necrotic cells. The early apoptotic cell death was observed by the compounds in all types of the treated cells. Compounds 5, 7 and 8 induced high percentage of necrosis towards all treated cells. The late apoptosis was recorded as a high rate after treatment with compound 3 in HepG-2 cells.


Published online: 5th April, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14450
Facile Access to Highly-Substituted Dihydrofurans Using Resonated Vinylpentanedione Radicals Generated by Mn(III)-Based Oxidation

Sousuke Oka, Shintaro Hashimoto, Kazuki Hisano, and Hiroshi Nishino*

*Department of Chemistry, Graduate School of Science, Kumamoto University, Kurokami 2-39-1, Chûou-Ku, Kumamoto 860-8555


Useful and easy access to highly-substituted dihydrofurans, which convert into various acetals, was established using the common Mn(III) oxidation. The key point is to use resonated vinylpentanedione radicals that cyclize to produce the desired acetoxydihydrofurans which are transformed into the hemiacetals and acetals in good yields under very mild conditions.

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Published online: 2nd April, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14423
An Efficient SeO2/FeCl3 Promoted Acylation:Intramolecular Friedel-Crafts Reaction Leading to a One-Pot Synthesis of Wrightiadione and Its Derivatives

Huan Zhang, Qi Wang, Lu Huang, Ziye Tian, Shunguang Zhang,* and Youlai Zhang*

*Tianjin Key Laboratory of Drug Targeting and Bioimaging, School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384, P.R. China.


Wrightiadione has been shown to exhibit a broad range of biological activities. An efficient and straightforward synthetic method for generating wrightiadione and its derivatives which contain a unique tetracyclic isoflavone moiety was developed. This unprecedented one-pot route utilizes a wide spread of substrates through three-step tandem Riley oxidation/Friedel-Crafts reaction/oxidation with SeO2/FeCl3 in moderate yield.

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Published online: 1st April, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14428
Synthesis and Properties of Fused Triad Donors Composed of Two 1,3-Dithiole[5]radialenes and Extended Tetrathiafulvalene

Kohei Kagawa, Takayuki Higashi, Aya Yoshimura, and Yohji Misaki*

*Department of Applied Chemistry, Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan


Synthesis of fused triad donors composed of two 1,3-dithiole[5]radialenes and one vinyl-extended or thiophene-inserted teterathiafulvalene (5, 6) have been successfully synthesized. Both donors exhibited simultaneous eight-electron oxidation attributed to simultaneous oxidation of two extended 1,3-dithiole[5]radialene units.


Published online: 30th March, 2021

Review | Regular issue | Prepress
DOI: 10.3987/REV-21-955
The Fascinating Chemistry of Mesoionic 4-Trifluoroacetyl-1,3-oxazolium-5-olates and Related Compounds

Ryosuke Saijo and Masami Kawase*

*Faculty of Pharmaceutical Sciences, Matsuyama University, 4-2 Bunkyo-cho, Matsuyama, Ehime 790-8578, Japan


This review illustrates the unexpected and unique transformation of mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (4-TFMK-münchnones) on treatment with different nucleophiles. A trifluoromethyl group that cannot be synthesized by the usual methods is incorporated in the products. The research discussed in this review is focused on the rich chemistry of 4-TFMK-münchnones. In particular, we highlight the recent advances in their use in contemporary organic synthesis, primarily of trifluoromethyl-substituted heterocycles. The chemistry of related mesoionic compounds is also discussed.


Published online: 30th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14421
Secoiridoid Glucosides Esterified with a Phenolic Glucoside from Alstonia macrophylla

Atsuko Itoh, Eri Kawaguchi, Sayo Nishio, Kaori Tani, Misaki Uchigaki, Marina Nakamura, Toru Akita, Toyoyuki Nishi, and Takao Tanahashi*

*Kobe Pharmaceutical University, 4-19-1, Motoyamakita-machi, Higashinada-ku, Kobe 658-8558, Japan.


Eleven novel secoiridoid glucosides, O-methylfrachinoside (1) and alstomacrosides A–J (211) were isolated, together with seventeen known compounds, from the dried twigs of Alstonia macrophylla. The structures of the new compounds were established on the basis of 1D and 2D NMR spectroscopic data. These compounds were commonly characterized as esters of secoxyloganin with a phenolic glucoside.


Published online: 30th March, 2021

Communication | Regular issue | Prepress
DOI: 10.3987/COM-21-14433
Acylative Desymmetrization of Glycerol Derivatives by Chiral DMAP Derivatives

Hiroki Mandai,* Kosuke Ashihara, Koichi Mitsudo, and Seiji Suga*

*Department of Pharmacy, Faculty of Pharmacy, Gifu University of Medical Science, 4-3-3 Nijigaoka, Kani, Gifu, 509-0293


An efficient enantioselective acylative desymmetrization of glycerol was developed by using a chiral DMAP derivatives 1e having a 1,1ʹ-binaphthyl unit. The reactions required only 0.1 mol% of the catalyst and showed moderate to good enantioselectivity (up to 94:6 er). Control experiments revealed that the first acylation of a glycerol derivative proceeded selectively rather than the second acylation to give diacylate.

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Published online: 30th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14443
Facile Preparation of 2-Aryl-3-iodopyrroles with N-Tosyl 4-Aryl-3-butyn-1-ylamines, I2, and tBuOK

Kaho Shibasaki, Hiroki Naruto, and Hideo Togo*

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


Treatment of N-tosyl 4-aryl-3-butyn-1-ylamines with I2 and K2CO3, followed by the reaction with tBuOK under mild conditions gave 2-aryl-3-iodopyrroles in good yields. The present approach is a one-pot method for the preparation of 2-aryl-3-iodopyrroles from N-tosyl 4-aryl-3-butyn-1-ylamines, which could be easily prepared from aryl iodides, N-(3-butyn-1-yl)phthalimides, and p-toluenesulfonyl chloride.

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Published online: 29th March, 2021

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)8
Recent Development on the Ring Transformation Reactions: Synthesis of Functionalized Benzenes, N-Heterocycles and Fused Ring Systems

Priyanka B. Kole and Fateh V. Singh*

*Chemistry Division (SAS), VIT Chennai, Vandalur-Kelambakkam Road, Chennai, Tamil Nadu, India


Ring transformation reactions using 2H-pyran-2-ones as valuable synthetic precursor with several nucleophiles for designing numerous interesting scaffolds is a growing field in synthetic organic chemistry. 2H-Pyran-2-ones has tendency to act as very good Michael acceptor and hence functions as good electrophile. The scope of 2H-pyran-2-ones has been explored for the synthesis of various molecules owning significant biological importance. Additionally, their synthetic potential has been discovered for the construction of interesting photophysically active molecules. From this point of view, the development of simple and environmental benign ring transformation strategy is a dynamic research field until today. This short review describes an overview of the most recent advances in ring transformation of functionalized 2H-pyran-2-ones into valuable aromatic scaffolds like functionalized benzenes, N-heterocycles and fused ring systems.

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Published online: 29th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14420
Synthesis, Photochemical Properties, and Cytotoxicity of 10-Alkylphenazin-2(10H)-ones

Haruki Kohatsu, Shogo Kamo, Takuya Hosokai, Shinji Kamisuki, Yutaro Machida, Ryota Kobayashi, Tsuneomi Kawasaki, Kenji Ohgane, and Kouji Kuramochi*

*Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan


In the present study, the synthesis of a variety of 10-alkylphenazin-2(10H)-ones by oxidative coupling between N-alkylbenzene-1,2-diamine and 1,2,4-benzenetriol under an oxygen atmosphere was realized, and their photochemical and biological properties were investigated. 10-Methylphenazin-2(10H)-one, a reddish orange pigment, exhibited fluorescence in the visible light region upon exposure to ultraviolet light. Interestingly, the fluorescence from 10-methylphenazin-2(10H)-one consisted of two components. In addition, the cytotoxic evaluation of various synthetic compounds was performed. Among the compounds tested in this study, 10-methylphenazin-2(10H)-one exhibited the most selective cytotoxic activity against human cancer A549 cells compared to normal MRC-5 cells.

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Published online: 26th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14390
Purification of High-Purity 2-Mercaptobenzothiazole by Two-Steps

Zengbing Zhao, Bo Chen, Lanxing Cheng,* Yili Zhao, Yongli Chai, and Shucheng Yang

*Henan Chemical Industry Research Institute Co., Zhengzhou, 450052, China


High-purity 2-mercaptobenzothiazole (2-MBT) is prepared from crude 2-MBT by aniline method under high pressure by solvent crystallization and deep impurity removal. For the first step of toluene purification, the semi-finished 2-MBT with excellent purity and yield can be obtained when the temperature of toluene solution reaches 100 oC and the content of toluene is about 1.5 times of that of crude 2-MBT. For the second step of deep purification, the by-products of semi-finished 2-MBT could be further removed by Na2SO3 when the mass ratio of water, the 2-MBT and Na2SO3 is 2: 1: 0.12 and the reaction condition is under 100 oC for 0.75 h. As a result, the purity and yield of 2-MBT can reach 99.9% and 97.3%, respectively. The preparation of high-purity 2-MBT would further optimize the market demand and meet the quality standard requirements for the development of other pharmaceutical intermediates or fine chemicals. This strategy solves the current problem of purification 2-MBT, and develops a new process technology route for the production of high-purity 2-MBT.


Published online: 26th March, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(K)74
Decisive Effects of C-N Axial Chirality of Intermediary Enolates on the Stereochemical Course of β-Lactam Formation from β-Branched α-Amino Acid Derivatives via Memory of Chirality

Ryuichi Hyakutake, Tomoyuki Yoshimura, Takahiro Sasamori, Norihiro Tokitoh, Kazuhiro Morisaki, and Takeo Kawabata*

*Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan


Stereochemistry of β-lactam formation of β-branched β-amino acid derivatives via a MOC strategy was investigated. The 4-exo-trig cyclization of axially chiral enolates generated from l-threonine and l-allo-threonine derivatives proceeded predominately with inversion of the configuration at the newly formed tetrasubstituted carbon, irrespective of the chirality at the β-carbon of the β-lactam precursors. These results indicated that C–N axial chirality of the intermediary enolates generated from the α-amino acid derivatives has decisive effects on the stereochemical course of β-lactam formation even in the presence of an sp3-chiral center at the β-carbon.

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Published online: 26th March, 2021

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14435
Anti-Tobacco Mosaic Virus Isoindolin-1-ones from the Stems of Nicotiana Tabacum

Jian-Duo Zhang, Xin Liu, Li Xu, Jia-Rui Jiang, Le-Le Deng, Wen-Wu Yang, Xue-Mei Li, Guang-Yu Yang, Tao Zhou,* and Feng-Xian Yang*

*Technology Center, China Tobacco Yunnan Industrial Co., Ltd., Kunming, Yunnan 650231, China


Three new (1-3) and three known (4-6) isoindolin-1-ones were isolated from the stems of Nicotiana tabacum. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1-3 were tested for their anti-tobacco mosaic virus (anti-TMV) activitiy. The results showed that compounds 1-3 showed high anti-TMV activity with inhibition rates of 42.6, 46.7 and 38.5% at the concentration of 20 μM, respectively. These rates are higher than that of ningnanmycin, a positive control.

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Published online: 25th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14422
Synthesis and Evaluation of Dendroamide A and Three Regioisomeric Analogs Having a Reversed Azole Ring as P-Glycoprotein Inhibitors

Takuji Magata, Yoshimi Hirokawa, Yuki Rokuhara, Ryota Nakayama, Rina Takahashi, Masashi Nogami, Yasuto Tai, Tomoki Imahori, Takanori Hashizume, and Naoyoshi Maezaki*

*Faculty of Pharmacy, Osaka Ohtani University, 3-11-1 Nishikiori-Kita, Tondabayashi, Osaka 584-8540, Japan


We have synthesized dendroamide A and three new analogs having a differently oriented azole moiety to reveal the effect of the orientation of the azole rings on the P-glycoprotein inhibitory activity. The appropriate assembly of modified azole units and dimers from natural-type azole units is examined. Although linear trimers including a modified thiazole unit were hard to cyclize compared with a derivative containing a modified oxazole unit, the yields of cyclization were successfully improved by changing the reaction conditions or the position of ring closure. Evaluation of P-glycoprotein inhibitory activity also reported.

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Published online: 24th March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14408
Copper Corrole Catalyzed Esterification of C(sp3)-H with Carboxylic Acids via Cross-Dehydrogenative Coupling Reaction

Zhao-Yang Liu, Wei-Yu Peng, Waseem Akram, Jia-Wei Lai, Hao Zhang, and Hai-Yang Liu

*Department of Chemistry, The Key Laboratory of Fuel Cell Technology of Guangdong Province, South China University of Technology, Guangzhou 510640, China


Copper corrole complex was firstly used as catalyst for oxidative esterification of un-reactive C(sp3)-H bond of cyclic ether and carboxylic acid via cross dehydrogenative coupling (CDC) reaction using di-tert-butyl peroxide (DTBP) as oxidant. A wide range of carboxylic acids can react with cyclic ether with good to excellent yields, showing copper corrole is a new kind of promising catalyst for CDC reaction. Under gram-level test, the turnover number (TON) may achieve 8400 with 84% yield at only 0.01% catalyst loading, demonstrating its practical uses.

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Published online: 23rd March, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)72
Claisen Rearrangement of 4-Allyloxy-1-p-Methyxy Benzylpyrazole and Synthesis of Pyrazole-Fused 7-Membered Lactones

Hayato Ichikawa,* Hiroki Takashima, and Shoichi Shimizu

*College of Industrial Technology, Nihon University, 1-2-1, Izumi-cho, Narashino, Chiba 275-8575, Japan


Allyl 4-pyrazolyl ethers were subjected to the Claisen rearrangement that involved heating under microwave condition to prepare the corresponding products with regioselective allylation at 5-position of the pyrazoles in good yields. The rearrangement products were converted into 7-membered pyrazololactones having an oxygen atom at 4-position of pyrazole, via a hydroesterification reaction with Pd(OAc)2 and DPE-phos as ligand under 40 atm of CO/H2 (6:34) in moderate to excellent yields.


Published online: 23rd March, 2021

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)68
Chloroamidation of Alkenes Using Sodium Hypochlorite Pentahydrate and Its Application to Synthetic of Aziridines

Masayuki Kirihara,* Kouta Adachi, Yugo Sakamoto, Kazuki Tujimoto, Sho Yamahara, Ryoji Matsushima, Yukou Namba, Kosuke Sato, Takashi Kamada, Yoshikazu Kimura, and Shinobu Takizawa*

*The Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan


The reaction of alkenes with sodium hypochlorite pentahydrate (NaOCl·5H2O) and phosphoric acid (H3PO4) in nitrile solvents resulted in a chloroamidation reaction, producing -chloroamide derivatives in good yields without the use of a transition metal catalyst (up to 90%). N-Pivalazirizines were readily obtained from the resulting -chloroamide derivatives when they were reacted with lithium hexamethyldisilazide (LiHMDS).

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Published online: 23rd March, 2021

Review | Regular issue | Prepress
DOI: 10.3987/REV-21-957
Synthesis and Structure−Activity Relationship Study of Intervenolin, an Antitumor and Anti-Helicobacter Pylori Quinolone Natural Product

Takumi Watanabe*

*Institute of Microbial Chemistry, Tokyo (BIKAKEN), 3-14-23 Kamiosaki Shinagawa-ku, Tokyo 141-0021, Japan


This review article overviews the chemistry and biology of intervenolin, a quinolone natural product bearing unusual substituents. Intervenolin was isolated as a modulator of tumor–stroma interactions, communication between tumor cells and surrounding normal cells to regulate tumor-associated events including proliferation. The synthesis of intervenolin by the author employs thiocyanate–isothiocyanate rearrangement and Suzuki–Miyaura cross coupling as key reactions, which was utilized in structure–activity relationship studies. The SAR studies generated analogs that are effective in vivo. Moreover, several intervenolin and analogs also showed anti-Helicobacter pylori activity. Mechanistic aspects of these biological activities, and synthetic study on structurally related natural products by Spring and co-workers are also discussed.


Published online: 22nd March, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14430
Rhodium(I) N-Heterocyclic Carbene Complexes as Catalysts for the Anti-Markovnikov Hydroaminations of Styrene

Yetkin Gök, Beyhan Yiğit, Özlem Özeroğlu Çelikal, and Murat Yiğit*

*Department of Chemistry and Chemical Process Technologies, Vocational School of Higher Education, Adiyaman University, 02040-Adıyaman, Turkey


A series of new rhodium(I) complexes with benzimidazole based N-heterocyclic carbene (NHC) ligand were synthesized by reactions of benzimidazolium salts with [Rh(OMe)COD]2. The characterization of rhodium(I) complexes with the general formula [RhCl(NHC)(η4-1,5-cyclooctadiene)] was done by physicochemical and spectroscopic methods. All the synthesized complexes were tested as catalysts in the intermolecular hydroamination reactions between styrene with aromatic amines in ionic liquid. All of these complexes tested here are catalytically active for the intermolecular hydroamination of styrene with aromatic amines in ionic liquid. The anti-Markovnikov addition products were obtained selectively by using 1 mol% of the rhodium complex.


Published online: 18th March, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)55
Stereoselectivity of the Biginelli Reaction Catalyzed by Chiral Primary Amine: A Computational Study

Takayoshi Yoshimura, Maneeporn Puripat, Vudhichai Parasuk, and Miho Hatanaka*

*Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan


The Biginelli reaction catalyzed by a chiral compound is one of the most effective ways to form bioactive heterocycle compounds. High enantioselectivity was obtained using primary amine with a chiral diamine backbone as a chiral catalyst. To elucidate the origin of the enantioselectivity, we investigated the reaction pathways of this catalytic reaction using the density functional theory. We also focused on the transition states of the rate-determining step leading different stereoisomers. The rate-determining step was the proton transfer process accompanying the cyclization of the substrate, which was mediated by the amide moiety of the catalyst, and the orientation of the amide moiety was the reason for the enantioselectivity.


Published online: 15th March, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)50
Fasciospyrinadinone and Fasciospyrinadinol, Novel 3-Alkylpyridine Sesquiterpenoids from an Indonesian Marine Sponge, as Selective Growth Inhibitors of the Cancer Cells Under Nutrient Starvation

Hirokazu Matsumoto, Tomoya Hisa, Kazunari Toda, Ryosuke Ishida, Andi Setiawan, Masayoshi Arai, and Naoyuki Kotoku*

*College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan


On the guidance of the bioassay using PANC-1 cells adapted to the glucose starvation, two novel pyridine sesquiterpenoids named fasciospyrinadinone (1) and fasciospyrinadinol (2) were isolated from the Indonesian marine sponge of Petrosaspongia sp. The chemical structures of the compounds were established on the basis of the 1D and 2D NMR spectra data. Then, we accomplished the first total syntheses of 1 and 2. Compound 1 showed selective growth inhibitory activity against PANC-1 cells adapted to glucose starvation, with IC50 value of 13 µM.

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Published online: 15th March, 2021

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)73
Large-Scale Synthesis of Thio-Glucose-Conjugated Chlorin E6 for Photodynamic Therapy

Akihiro Nomoto,* Hiroaki Yamaguchi, Masato Masuda, Keisuke Hyakumura, Shintaro Kodama, Tomohiro Osaki, Yoshiharu Okamoto, Mamoru Tanaka, Hiromi Kataoka, Atsushi Narumi, Tomokazu Yoshimura, Shigenobu Yano, and Akiya Ogawa

*Engineering, Department of Applied chemistry, Osaka Prefecture University, Sakai, Osaka 593-8531, Japan


Chlorin e6 is a heterocycle exhibiting spectral absorption in the 600–700 nm wavelength range used for photodynamic therapy (PDT). Herein, a sugar-conjugated chlorin e6 derivative was synthesized on a large scale. An alkyl spacer was fabricated by controlling the alkylation conditions between the thio-sugar and chlorin e6 and thio-glucose-conjugated chlorin e6 was successfully synthesized.


Published online: 12th March, 2021

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)6
Combined Brønsted-Base-Mediated Direct C-H Carboxylation of Heteroarenes with Co2

Masanori Shigeno,* Keita Sasaki, Kazuya Hanasaka, Itsuki Tohara, Kanako Nozawa-Kumada, and Yoshinori Kondo*

*Graduate School of Pharmaceutical Science, Tohoku University, 6-3 Aobayama, Sendai 980-8578, Japan


This review article summarizes that the combined Brønsted-base system comprising LiO-t-Bu, CsF, and 18-crown-6 efficiently proceeds the direct carboxylation of electron-rich heteroarenes, such as benzothiophene and benzofuran, with CO2. Good functional group compatibility is displayed, allowing the use of Me, MeO, halogen, CN, ketone, and amide moieties. 3-Substituted indoles are also used for C-2 carboxylation, while double-carboxylation of 2-alkylheteroarenes is achieved by LiO-t-Bu and CsF.


Published online: 12th March, 2021

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)71
Gold-Catalyzed Formal [3+2]Cycloaddition of p-Quinones and 1-Phenylpropenes in Ionic Liquid: Environmentally Friendly and Stereoselective Synthesis of Benzofuran Neolignans

Nobuyoshi Morita,* Kanae Ikeda, Hitomi Chiaki, Ryuto Araki, Kosaku Tanaka III, Yoshimitsu Hashimoto, and Osamu Tamura*

*Laboratory of Organic Chemistry, Pharmaceutical Sciences, Showa Pharmaceutical University, 3-3165, Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan


Gold(III)-catalyzed formal [3+2] cycloaddition of p-quinones with 1-phenylpropenes in an ionic liquid, [EMIM][NTf2], enabled environmentally friendly, stereoselective synthesis of 2,3-dihydrobenzofuran neolignans in good yields. Moreover, the recycle of tThe gold catalyst in /ionic liquid was achievedcould be recycled at least five times, affording 2,3-dihydrobenzofuran in good yields.

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