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Published online: 22nd October, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)36
■ Preparation of 2-Aryl-3-Silyl- and 2-Aryl-3-Germyl-1,3-Butadienes via Arylnickelation and Zinciomethylation

Nana Yoshino, Betemariam Sharewa, Zenichi Ikeda, and Seijiro Matsubara*

*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan

Abstract

Benzyl 3-silyl(or germyl)propargyl ether, aryl iodide, and bis(iodozincio)methane were assembled in the presence of a nickel catalyst to efficiently give 2-aryl-3-silyl(germyl)-1,3-butadienes via arylnickelation, zinciomethylation, and 1,4-elimination of zinc benzyloxide. As a ligand, an electron-deficient phospine such as tris(2-furyl)phosphine was effective.

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Published online: 22nd October, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-940
■ Synthetic Approaches for Heteroannulated Chromones Fused Various Heterocyclic Systems

Salsabeel H. Hashiem, Magdy A. Ibrahim, Al-Shimaa Badran,* Nasser M. El-Gohary, and Hassan A. Allimony

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

Abstract

The main focus of this review summarized the different methods utilized for the synthesis of chromone annulated with different heterocyclic rings such as pyrroles, furans, pyrazole, imidazole, benzene, naphthalene, quinolone……and others.

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Published online: 21st October, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-935
■ The Interrupted Pummerer Reaction: Design of Sulfoxides and Their Utility in Organic Synthesis

Kazuhiro Higuchi* and Masanori Tayu

*Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

Acid anhydride-activated sulfoxides can undergo a variety of cascade reactions after reacting with nucleophiles on its sulfur atom. Originally regarded as an abnormal phenomenon that occurs under Pummerer reaction conditions, the reports of the reaction increased gradually, and research regarding sulfoxide reactivity has advanced. In recent years, the term ‘interrupted Pummerer reaction’ has been introduced, and the transformation has been actively incorporated into the development of new research areas. Such studies have yielded numerous valuable sulfoxides, which contribute to the precise reaction control and to the generation of practical products. Notably, the outcome of the interrupted Pummerer reaction is characteristic for each nucleophile.

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Published online: 20th October, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)31
■ Mn(III)-Based Oxidative Cyclization of 2-((2-Arylamino)Ethyl)Malonates: Synthesis of Quinolines via Dihydroquinolinedicarboxylates

Takayuki Nagashimada, Masahiro Morikawa, Kengo Ohki, and Hiroshi Nishino*

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

Abstract

The synthesis of quinolines from aniline derivatives via the Mn(III)-based oxidative cyclization of 2-(2-(arylamino)ethyl)malonates is described. The 2-(2-(arylamino)ethyl)malonates were prepared in two steps from the substituted anilines. The cyclization of nineteen arylaminoethylmalonates protected by the N-acyl and N-alkoxycarbonyl groups easily proceeded in the formal 6-endo mode regardless of the presence of halo, methyl, and methoxy groups on the aromatic ring, and the corresponding tetrahydroquinolinedicarboxylates were produced in high yields except for the 2,4-dimethoxyphenyl-substituted aminoethylmalonate which occurred by ipso-cyclization. The tetrahydroquinolinedicarboxylate could be transformed into quinoline via decarboxylation and deprotective hydrolysis. The characteristic phenomenon in the NMR spectrum of the tetrahydroquinolinedicarboxylates is also discussed.

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Published online: 20th October, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-942
■ Mini Review: Antioxidant Application of Metal-Organic Frameworks and Their Composites

Shaikha S. Alneyadi*

*Department of Chemistry, College of Science, UAE University Al-Ain, 15551 UAE

Abstract

Metal–organic frameworks (MOFs) are porous coordination materials composed of multidentate organic ligands and metal ions or metal clusters. MOFs have great potential as medical materials for biological, environmental, and food antimicrobial fields. In recent years, MOFs have been applied to various antioxidant fields due to their continued release capability, porosity, and structural flexibility in combination with many chemicals and/or materials such as nanoparticles, antioxidant, and polymers. This review offers a detailed summary of the antioxidant applications of MOFs and their composites, focusing on the combination types of MOF composites and their antioxidant effects in different applications described in 2015-2020. These applications are illustrated by the examples discussed in this review.

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Published online: 19th October, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)24
■ Rhodium-Catalyzed Crossed [2+2+2] Cycloaddition with Ynamides: Key-Strategy for The Concise Total Synthesis of 3-Oxygenated Carbazole Alkaloids

Carole Alayrac* and Bernhard Witulski*

*Laboratoire de Chimie Molèculaire et Thioorganique (LCMT)
, National Graduate School of Engineering and Research Center, , France

Abstract

Total syntheses of a set of naturally occurring 3-oxygenated carbazole alkaloids - 6-chlorohyellazole, carazostatin, carbazomycins A and B - are described. The key-strategy underlines a highly chemo- and regioselective rhodium-catalyzed [2+2+2] cyclotrimerization between appropriately tailored yne-ynamides and 1-methoxypropyne that is stirred by the interplay of stereoelectronic and steric effects allowing the introduction of four ring substituents of the natural carbazoles within a single step and making the overall syntheses short and efficient.

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Published online: 16th October, 2020

Communication | Regular issue | Prepress
DOI: 10.3987/COM-20-14346
■ Rhodium-Catalyzed Oxidative Olefination of N-(2-(4,5-dihydrooxazol-2-yl)phenyl)amides with Arylethenes via Extraordinary N-Aryl C-H Bond Functionalization

Hao Yan,* Fang-Peng Hu, Xiao-Qiang Zhou, Zhi Li, and Guo-Sheng Huang

*College of Pharmacy, Shaanxi University of Chinese Medicine, Xianyang, 712046, P. R. of China

Abstract

Amide-tethered aryloxazoline motifs are important structural moiety because of ubiquity in medicinal chemistry, functional materials and pincer ligands. In recent years, much attention about N-(2-(4,5-dihydrooxazol-2-yl)phenyl)amides has been focused on ortho C−H functionalization of amides. Herein a highly efficient rhodium(III) catalyzed oxidative olefination of N-(2-(4,5-dihydrooxazol-2-yl)phenyl)amides with arylethenes via extraordinary N-aryl C-H bond functionalization was developed.

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Published online: 15th October, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14342
■ Five New Highly Oxidized Neoclerodane Diterpenes, Salvileucalins E-I from Salvia Leucantha

Yutaka Aoyagi,* Yutaka Nakazato, Akira Yamazaki, Haruna Kondo, Ayana Ninomiya, Mari Tokuda, Haruhiko Fukaya, Reiko Yano, Koichi Takeya, and Yukio Hitotsuyanagi*

*College of Pharmacy, Kinjo Gakuin University, 2-1723 Omori, Moriyama-ku, Nagoya 463-8521, Japan

Abstract

Five new rearranged neoclerodane diterpenes (salvileucalins E-I) were isolated from Salvia leucantha (Lamiaceae), whose structures were elucidated by spectroscopic analysis and X-ray crystallographic analysis.

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Published online: 15th October, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14349
■ Synthesis of Novel Thienopyrimidines and Thienodiazepines from Ethyl 2,4-diamino-5-{[(2E)-2-(1-phenylethylidene)hydrazino]carbonyl}thiophene-3-carboxylate

Osama Farouk and Kamelia M. El-mahdy*

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

Abstract

Ethyl 2,4-diamino-5-{[(2E)-2-(1-phenylethylidene)hydrazino]-carbonyl}thiophene-3-carboxylate (3) was synthesized via Gewald reaction that can be readily used as precursor to potentially interesting thiophenes. Compound 3 reacted with cyanoacetamide and/or malononitrile producing thienopyrimidines 4 and 5, respectively. Reaction of compound 3 with hydrazinecarbodithioic acid afforded pyrimidothienotriazepine 6. Treatment of compound 3 with ethylenediamine and carbon disulfide gave (imidazolinyl)thiophene 7. The latter compound can be used as building blocks for the synthesis of various heterocycles. Structures of the newly synthesized compounds were deduced based on their analytical and spectral data.

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Published online: 7th October, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14337
■ Synthesis of Pyrrolo[2,3]pyrido[2,4-d]pyrimidin-6-ones and Related New Heterocycles

Tamás Zelenyák, Imre Fejes, Jérôme-Benoît Starck, and Nyerges Miklós*

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

Abstract

During our synthetic development work focused on new Bcl-2 inhibitor molecules an unexpected and interesting by-product was formed. Using this obsevation we have explored the synthesis of the hitherto unknown pyrrolo[2,3]pyrido[2,4-d]pyrimidin-6-one heterocyclic core. The study of the scope and limitations of this cyclisation resulted in other three new types of three membered heterocyclic ring systems.

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Published online: 6th October, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-941
■ Synthetic Methods for Phosphorus Compounds Containing Chromone and Thiochromone Rings

Tarik E. Ali,* Mohammed A. Assiri, Somaia M. Abdel-Kariem, and Ibrahim S. Yahia

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

Abstract

The chromone and thiochromone rings are prominent heterocyclic substructures present in numerous natural and pharmacologically active compounds. To date, many chromone analogues containing phosphorus compounds are interest in several laboratories due to their potent pharmacological activities. This review compiles all the available literature data on the synthesis of phosphorus compounds containing chromone and thiochromone rings as well as their available biological properties starting from their appearance up to the end of 2019.

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Published online: 23rd September, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)27
■ Dirhodium(Ii)-Catalyzed Ortho C–H Amination of N-Alkyldiarylamines

Motoki Ito,* Mamiko Mori, Tomoya Nakagawa, Miki Hori, Kazuhiro Higuchi, and Shigeo Sugiyama*

*Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588,

Abstract

Dirhodium(II)-catalyzed ortho C–H amination of N-alkyldiarylamines has been developed. The C(sp2)–H amination proceeded with high preference over C(sp3)–H amination to provide N-aryl-o-phenylenediamines in up to 80% yield. With the use of unsymmetric diarylamines as substrates, selective amination of one of two distinct aromatic rings was also achieved.

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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: 16th September, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)23
■ Synthesis of (Trifluoromethyldiazirinyl)phenyl-boronic Acid Derivatives for Photoaffinity Labeling

Manami Hashinoki, Natsumi Kurokawa, Yuta Murai, Zetryana Puteri Tachrim, Yasuko Sakihama, Takeyuki Suzuki, and Makoto Hashimoto*

*Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan

Abstract

Trifluoromethylphenyldiazirine is one of the most reliable photophores for photoaffinity labeling during functional analysis of biologically active compounds. Phenylboronic acid derivatives containing trifluoromethyldiazirinyl moiety have not yet been reported. The construction of the photophore was achieved using (3-formylphenyl)boronic acid and (4-formylphenyl)boronic acid pinacol esters effectively.

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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: 11th September, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)26
■ Transition Metal-Free O-Arylation of Quinoxalin-2-ones with Diaryliodonium Salts

Masami Kuriyama,* Yuki Mochizuki, Tsubasa Miyagi, Kosuke Yamamoto, Yosuke Demizu, and Osamu Onomura*

*Graduate School of Biomedical Sciences, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

The transition metal-free O-arylation reactions of quinoxalin-2-ones with diaryliodonium salts have been achieved, and desired 2-aryloxyquinoxalines were readily obtained in moderate to high yields. This method proved to be compatible with a series of diaryliodonium salts as well as a set of quinoxalin-2-ones.

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Published online: 9th September, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)19
■ An Alternative Approach to the Development of Near-Infrared Fluorescent Dyes Based on Fluorescein

Akane Katori, Akari Yamagami, Sae Wakabayashi, Kouji Kuramochi, Ayumi Imayoshi, and Kazunori Tsubaki*

*Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Japan

Abstract

In xanthene dyes the upper aryl moiety is often a benzene ring, but in this work an L-shaped dibenzoxanthene dye (4) was synthesized with a five-membered (benz)imidazole ring as the upper aryl moiety. Although 4 was designed with the π-face of the dibenzoxanthene and the π-plane of the aryl moiety as coplanar, the reactivity of the compound at the triaryl carbon was quite high and easily attacked by solvent, such as methanol. The consequent discoloration is caused not only by the external exposure of the triaryl carbon, but also by the greatly reduced LUMO level and increased reactivity to nucleophilic attack when the π-system of the xanthene ring is expanded. The introduction of the 2,6-dimethylphenyl group was found to be effective to avoid nucleophilic attack by solvent. A compound, labeled 9c, with a 2,6-dimethylphenyl group as the aryl moiety, had sufficient stability to solvent, an emission maximum at 828 nm in DMF, and a fluorescence quantum yield of 8%.

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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: 4th September, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)25
■ Palladium on Carbon–Catalyzed Oxidative Transformation of Benzylic Ethers

Ryoya Takakura, Shoko Kuwata, Kouki Nakano, Naoki Yasukawa, Hironao Sajiki,* and Yoshinari Sawama*

*Laboratory of Organic Chmistry, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi 501-1196, Japan

Abstract

Palladium on carbon (Pd/C)-catalyzed oxidative transformations of primary and secondary benzylic ethers in ethylene glycol as a solvent and reagent in an oxygen atmosphere produced the corresponding hydroxyethyl esters and cyclic ketals, respectively. Commercially-available and heterogeneous Pd/C was easily removed by filtration, and molecular oxygen was used as a clean oxidant.

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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: 2nd September, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)16
■ The Effect of the Base Triplets Adjacent to a T•CG or 5-MethylC•CG Triplet in the Triplex DNA

Yuta Ito, Chisa Hama, Takashi Osawa, and Yoshiyuki Hari*

*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan

Abstract

The effect of the base triplets adjacent to an X•CG triplet [X = T, 5-methylcytosine (C), or their LNA and ENA counterparts] in a triplex DNA was examined through the UV-melting experiments. Whereas the triplex containing a T•CG triplet, sandwiched by T•AT triplets, was stable, the replacement of T•AT with C•GC at the 5ʹ-adjacent site significantly destabilized the stability. When one or both of the adjacent T•AT triplets were replaced with C•GC, the triplexes containing a C•CG triplet were generally more stable than those containing a T•CG triplet. Further increases in the thermal stability of the triplexes were observed by LNA and ENA modifications. These results suggested that a C•CG triplet rather than a T•CG triplet would be suitable for triplex formation when C•GC triplets existed at its adjacent site.

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Published online: 27th August, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)20
■ Transition-Metal-Free Aziridination of Alkenes with Sulfamate Esters Using tert-Butyl Hypoiodite

Kensuke Kiyokawa,* Shogo Nakamura, and Satoshi Minakata*

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Abstract

The transition-metal-free aziridination of alkenes with sulfamate esters in the presence of tert-butyl hypoiodite (t-BuOI) is reported. The reaction can be used in intra- and intermolecular reactions, offering a practical and environmentally benign method for the synthesis of valuable aziridine compounds.

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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

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) A–G 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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