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Published online: 28th March, 2022

Review | Special issue | Prepress
DOI: 10.3987/REV-21-SR(R)2
The Utility of Oxoammonium Species in Organic Synthesis: Beyond Alcohol Oxidation

Shota Nagasawa, Yusuke Sasano, and Yoshiharu Iwabuchi*

*Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3, Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan

Abstract

Oxoammonium species are electrophilic chemical species generated via single electron oxidation of nitroxyl radicals. Although this species and its salts are known as useful oxidants and active species for (catalytic) oxidation of alcohols into carbonyl compounds in organic synthesis, the benefits of oxoammonium species for the oxidative transformations of numerous types of substrates apart from alcohols has been reported. This review summarizes the synthetic utility of oxoammonium species under both stoichiometric and catalytic conditions with the exception of alcohol oxidation.

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Published online: 25th March, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14647
FAB-MS Measurement of 2-Hydroxyestrone and Monosaccharides Assisted by 4-Pyridineboronic Ester Derivatization

Sachiko Komatsu, Katsuhiko Sato,* Kyoko Sugiyama, Masayuki Kumano, Kazuhiro Watanabe,* and Tsutomu Fujimura

*Laboratory of Synthetic and Medicinal Chemistry, Department of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

Phenylboronic acid (PBA) reacts specifically with diol compounds such as sugars. Compared with general derivatization, boronic ester derivatization has the advantage of being a simple procedure and requires fewer resources for sample pretreatment. To improve the detection sensitivity and selectivity for diol compounds in mass spectrometry, we investigated the effect of boronic ester derivatization of diol compounds on the detection sensitivity. As a result, several proton-affinitive boronic acids were examined, and the peak intensities of the ions associated with 2-hydroxyestrone were observed with 4-pyridineboronic acid as the reagent. The 4-pyridineboronic ester derivatization approach was found to be a useful labeling method for FAB-MS measurements due to the proton and diol affinity from the heterocyclic moiety.

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Published online: 24th March, 2022

Paper | Special issue | Prepress
DOI: 10.3987/COM-22-S(R)16
Construction of Tetrahydroquinolines with Spirocyclic Structures at the 4-Position

Yuko Wakahara, Takahiro Noro, Juri Sakata, Hirofumi Ueda, and Hidetoshi Tokuyama*

*Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, Japan

Abstract

The construction of tetrahydroquinolines with a spirocyclic structure at the 4-position was studied. The five-step sequence includes construction of benzocyclopentanone oxime by Knoevenagel condensation of cyclic ketones with Meldrum’s acid followed by Michael addition of aryl Grignard Reagent, intramolecular Friedel–Crafts acylation, condensation with hydroxylamine, and reductive ring expansion reaction using diisobutylaluminium hydride. The utility of this method was demonstrated by construction of a variety of tetrahydroquinolines possessing a four to eight-membered spirocyclic ring as well as adamantane and indane structures at the 4-position.

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Published online: 22nd March, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14642
Access to Functionalized Pyrrolophenanthridine via an ortho C-H Amination/Interannular C-H Arylation Cascade of N-Arylpyrroles

Jitan Zhang,* Yuhang Li, Pengpeng Sun, Yue Zhang, Meihua Xie,* and Jiaping Wu*

*College of Chemistry and Materials Science, Anhui Normal University, 189 Jiuhua Nan Road, Wuhu, Anhui, 241002, China

Abstract

An expeditious access to pyrrolophenanthridine scaffold enabled by a Catellani strategy from N-arylpyrroles and O-benzoylhydroxylamines is disclosed. This reaction proceeds smoothly involving an ortho C-H amination/interannular C-H arylation cascade and well tolerates a number of pyrrole and amine substrates. Furthermore, the potential of this protocol has been highlighted by the easily accessible scale-up synthesis and a plausible mechanism of this reaction was also proposed.

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Published online: 10th March, 2022

Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14640
Supramolecular Chirogenesis in Amide-Linked Bis(Zinc Porphyrin): Application for Absolute Configurational Assignment of Chiral Calboxylic Acids and Chiral Amino Acids

Satoshi Hayashi,* Shiori Takeda, Takahiro Namba, Masahiro Noji, and Toshikatsu Takanami*

*Department of Life and Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

A facile and derivatization-free method for determining the absolute configurations of a chiral carboxylic acid was developed by a supramolecular exciton-coupled circular dichroism (ECCD) protocol using the amide-linked bis(zinc porphyrin) BP2 as a hydrogen-bonding host molecule. Using a proposed working model, the stereochemistry of various carboxylic acids and N-protected amino acids can be determined nonempirically.

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Published online: 8th March, 2022

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)9
Improved Synthesis of Naldemedine Tosylate and Crystal Structures of Four Related Solid Forms

Josef Spreitz, Thomas Gelbrich, Sven Nerdinger,* Marijan Stefinovic, and Ulrich J. Griesser

*Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

The production of drug substances requires a robust and scalable process capable of delivering the active pharmaceutical ingredient (API) in excellent chemical and polymorphic purity. With this goal in mind we have developed an improved procedure for the preparation of naldemedine tosylate, which crystallizes directly from the reaction mixture as pure polymorph form II. Solid state studies revealed a series of additional new physical forms whose crystal structure have been determined by single-crystal X-ray diffraction.

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Published online: 8th March, 2022

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-22-S(R)10
Synthesis of N3-Substituted Quinazoline-2,4-diones via C-4 Amination-Cyclization of Isatoic Anhydrides

Nittaya Wiriya, Dolnapa Yamano, Surat Hongsibsong, Mookda Pattarawarapan, and Wong Phakhodee*

*Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand

Abstract

A direct approach for the synthesis of N3-substituted quinazoline-2,4-diones via condensation of isatoic anhydrides with amines mediated by Ph3P-I2 was reported. Instead of the expected benzoxazinones, the reaction proceeds with an amine attack at the C-4 position of isatoic anhydrides leading to quinazoline-2,4-diones upon heating in the presence of base. This one-pot process enables a rapid construction of a broad range of quinazoline-2,4-dione derivatives using simple, readily available, and low-cost reagents with no extra carbonylating agent needed.

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Published online: 7th March, 2022

Review | Special issue | Prepress
DOI: 10.3987/REV-22-SR(R)5
Heterocyclic Stilbene and Bibenzyl Derivatives in Liverworts: Distribution, Structures, Total Synthesis and Biological Activity

Yoshinori Asakawa* and Fumihiro Nagashima

*Institute of Pharmacognosy, Tokushima Bunri University, Tokushima 770-8514, Japan

Abstract

Liverworts are a rich source of lipophilic terpenoids, and aromatic compounds especially bibenzyl and bis-bibenzyl derivatives. This review is concerned with the distribution of heterocyclic stilbenes and bibenzyls in liverworts, belonging to the Acrobolbaceae, Aytoniaceae, Frullaniaceae, Lejeuneaceae, Plagiochilaceae, and Radulaceae families. Some Radula species elaborate bibenzyl cannabinoids, which possess remarkably similar biological activity to that of the Δ9-tetrahydrocannabinoids, the psycho- and anti-inflammatory active metabolites found in Cannabis sativa.

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Published online: 3rd March, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-21-14606
Synthesis and in vitro Anticancer Efficacy of Novel Silibinin Derivatives

Jiang Zeng, Qiuchan Wu, Jinfu Dong, Cong Liang, Xiaomou Wei, Jifei Chen, Song Shi, Zhijie Yang, Tian Lan, and Hongwen Wu*

*Pharmacy, The Fourth Affiliated Hospital of Guangxi Medical University, No.1 Liushi Road, China

Abstract

A series of eleven novel silibinin derivatives bearing alkynyl or sulfonyl groups were successfully designed and synthesized, and most of them suppressed the proliferation of MCF-7, NCI-H1299, HepG2 and HT29 by CCK-8 assay. Especially 3a and 5b were determined to be the most effective derivatives in the tested series with IC50 values of 7.41 and 3.37 μM against MCF-7 and HepG2 cells, respectively. In addition, a structure-activity relationship (SAR) study revealed that monosubstituted derivatives exhibited more potent anticancer activity than multiple substituted derivatives. The proliferation inhibitory activity can be improved by oxidative dehydrogenation of silibinin derivatives. The present findings suggest C7-OH monosubstituted silybin or 2,3-dehydrosilibinin derivatives with alkynyl or sulfonyl groups would be promising for further development as an anticancer agent.

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Published online: 2nd March, 2022

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-22-14626
Concise Semi-Synthesis of a Flavone Glycoside from Marine Angiosperm

Lisha Wu, Shiqiang Yan,* and Limei Huang

*College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China

Abstract

Starting from commercially available scutellarin, a natural flavonoid glycoside 6-hydroxyapigenin-7-O-(6”-O-(E)-coumaroyl)-β-glucopyranoside was semi-synthesized in a linear 6-step sequence with an overall yield of 31.5%. This work definitely laid the foundation for the further pharmacological study of this natural compound.

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Published online: 17th February, 2022

Review | Special issue | Prepress
DOI: 10.3987/REV-22-SR(R)3
Alkaloids and Alkaloid-Like Compounds Are Potential Scaffolds of Antiviral Agents against SARS-CoV-2 (COVID-19) Virus

Prasat Kittakoop,* Dhanushka Darshana, Rapeepat Sangsuwan, and Chulabhorn Mahidol

*Chulabhorn Graduate Institute, Program in Chemical Sciences, Chulabhorn Royal Academy, Kamphaeng Phet 6 Road, Laksi, Bangkok 10210, Thailand

Abstract

COVID-19 pandemic has an enormous impact on humans, and it has disrupted daily life of people. Moreover, COVID-19 pandemic has significant negative effects on the world economics. To prevent the viral infection, vaccines are rapidly developed and available for certain strains of SARS-CoV-2 virus. However, the emerging of new variants has caused the problems for COVID-19 vaccines due to immune escape ability, challenging the vaccine development process which usually takes years. In this regard, there is a critical need of new antiviral compounds that can be used to combat SARS-CoV-2 virus safely and effectively. This review provides an overview on alkaloids and alkaloid-like compounds, which have antiviral activity against SARS-CoV-2 virus and related coronaviruses. Drug repurposing has played a crucial role for the drug discovery of COVID-19, and many effective antiviral agents against SARS-CoV-2 virus are from commonly used drugs or antiviral leads. Antiviral natural alkaloids and derivatives, which have the activity toward SARS-CoV-2 virus and related coronaviruses, are also discussed in this review.

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Published online: 15th December, 2021

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)8
Abnormal Strecker Reaction of 3-formylindole and Aniline

Tomohiro Yazawa, Masaya Nakajima,* and Tetsuhiro Nemoto*

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan

Abstract

Reaction of 3-formylindole, aniline, and TMSCN under conditions of the Strecker reaction yielded a Friedel-Crafts reaction product rather than the usual aminonitrile. This abnormal Strecker reaction can be applied to various aniline and 3-formylindole derivatives. DFT calculations revealed that the most thermodynamically stable product is generated in the reaction.

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Published online: 2nd December, 2021

Communication | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)7
The Synthesis of Simplified Analogues of Crambescin B Carboxylic Acid and Their Inhibitory Activity of Voltage-Gated Sodium Channels: New Aspects of Structure–Activity Relationships

Atsuo Nakazaki,* Shunsuke Mouri, Yoshiki Nakane, Yuki Ishikawa, Mari Yotsu-Yamashita, and Toshio Nishikawa

*Faculty of Science and Engineering, Iwate University, Ueda, Morioka 020-8551 (Japan)

Abstract

We describe the synthesis of six new analogues of crambescin B carboxylic acid from L-aspartic acid and the elucidation of their structure-activity relationships by a cell-based colorimetric assay. All the synthesized analogues except for the C4-analogue were found to have inhibitory activities against voltage-gated sodium channels (VGSCs) in nM order in a cell-based colorimetric assay.

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Published online: 8th September, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)6
Application of Reversible Detection Method for N-terminus Amino Groups: Solid Phase Synthesis of Stylissatin B

Ao Tan, Keigo Takamatsu, Fusheng Xu, Seren Osanai, and Hiroyuki Konno*

*Department of Biological Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan.

Abstract

The first synthesis of the proline-rich cyclic heptapeptide stylissatin B is described. Reversible detection method of N-terminus amino groups using tetrachloro-N-hydroxyphthalimide was applied as the Fmoc-solid phase peptide synthesis. The end points of all reactions of solid support could be pursued by the detection methods.

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Published online: 17th August, 2021

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)4
Isolation of Ikahonone, 4-methyl-2,4-dihydroxy-3-pentanone from Bacillus cereus IFM12235

Yasumasa Hara, Mareno Chiba, Keiichiro Watanabe, and Masami Ishibashi*

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan

Abstract

A new ketone, ikahonone (1), and five known compounds (2-6) were isolated from Bacillus cereus IFM12235 collected in Japan. The structure of compound 1 was elucidated using spectral studies, including NMR. The absolute configurations of 1 and 2 were determined by comparing electronic circular dichroism (ECD) spectra with known compounds and calculating the ECD spectra of 1 and 2. Three compounds (2-4) were previously prepared by synthesis, and first isolated as natural products in the present study.

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Published online: 11th August, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)5
Azuleno[6,5-b]indoles: Palladium-Catalyzed Oxidative Ring-Closing Reaction of 6-(Arylamino)azulenes

Taku Shoji,* Yukino Ariga, Shunji Ito, and Masafumi Yasunami

*Department of Science, Graduate School of Science and Technology, Shinshu University, Matsumoto 390-8621, Nagano, Japan

Abstract

6-Bromoazulene derivative with two n-butoxycarbonyl groups was prepared by the modification procedure of Nozoe’s azulene synthesis. The aromatic nucleophilic substitution reaction of the 6-bromoazulene derivatives having two-ester functions with aniline derivatives proceeded to give the corresponding 6-(arylamino)azulene derivatives. Palladium-catalyzed oxidative ring-closing reaction of the 6-(arylamino)azulene derivatives provided the azuleno[6,5-b]indoles in moderate to good yields.

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Published online: 22nd June, 2021

Communication | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)3
Synthesis and Optical Properties of Azuleno[1,2-b]benzothiophene and Selenophene

Mio Matsumura,* Taiki Kamiya, Masato Kawakubo, Yukako Hayashi, Tadashi Hyodo, Yuki Murata, Kentaro Yamaguchi, and Shuji Yasuike*

*School of Pharmaceutical Sciences, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan

Abstract

Benzothiophene- and benzoselenophene-fused azulene derivatives were synthesized by Cu-catalyzed tandem cyclization via the Ullmann-type S/Se– arylation and Csp2–H chalcogenation of 2-(2′-bromophenyl)azulene. The maximum absorption of tetracyclic products was red-shifted from that of 2-phenylazulene, which does not contain a bridged chalcogen atom. Single-crystal X-ray analysis of azuleno[1,2-b]benzoselenophene revealed that the benzo[b]selenophene and azulene rings are almost coplanar.

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Published online: 1st June, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)2
New Sugar Based γ-Amino Silyl Ether Organocatalysts for Asymmetric Michael Addition of β-Keto Esters with Nitroolefins

Divakar Ganesan, Perumalsamy Parasuraman, Zubeda Begum, Rajkumar Thiyagarajan, Chigusa Seki, Yuko Okuyama, Eunsang Kwon, Koji Uwai, Michio Tokiwa, Suguru Tokiwa, Mitsuhiro Takeshita, and Hiroto Nakano*

*Graduate School of Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran 050-8585

Abstract

New sugar based γ-amino silyl ether organocatalysts were synthesized and their catalytic ability was examined in asymmetric Michael addition of β-keto esters with nitroolefins affording chiral Michael adducts with quaternary carbon stereocenter in good to excellent chemical yields, diastereoselectivities and moderate enantioselectivities (up to 97%, up to dr. 85:15, up to 56% ee).

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Published online: 27th May, 2021

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-21-S(R)1
Lipase-Catalyzed Site-Selective Deacetylation of 2-Methoxy-3-methylnaphthalene-1,4-diol Diacetate for Construction of Characteristic Substituted 1,2,3,4-Tetrahydroisoquinoline Derivative of Novel Ecteinascidin Marine Natural Product

Masashi Yokoya,* Ryo Sato, and Naoki Saito

*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

We developed a site-selective deacetylation of 2-methoxy-3-methylnaphthalene-1,4-diol diacetate catalyzed by Candida antarctica lipase B, which furnished 1-hydroxy-2-methoxy-3-methylnaphthalen-4-yl acetate in 88% yield. This product was transformed into 2-methoxy-3-methylnaphthalen-1-ol in a five-step sequence (30.5% overall yield from 7a). It is a novel procedure for preparing a characteristic A ring substituted system for both safracin antibiotics (2) and ecteinascidin marine natural products (1).

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