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Published online: 25th January, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)49
■ Stereoselective Synthesis of Diastereomeric Berberine Alkaloids, O-Methylcorytenchirine and Coralydine

Misaki Kirii, Junpei Matsuoka, Akari Miyawaki, Kiyoshi Tomioka, and Yasutomo Yamamoto*

*Faculty of Pharmaceutical Sciences, Department of Medicinal Chemistry, Doshisha Women’s College of Liberal Arts, Kodo, Kyotanabe, Kyoto 610-0395, Japan

Abstract

Racemic total synthesis of diastereomeric berberine alkaloids, O-methylcorytenchirine and coralydine, was achieved from the common isoquinoline intermediate of norlaudanosine. The relative stereochemistry of C8-C14 was successfully constructed by favorable axial attack of nucleophiles to the iminium of dihydroprotoberberines.

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Published online: 25th January, 2021

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)67
■ Synthesis of 1-Azaazulenes Using Ring-Opening Cyclization of Spirocyclopropane with Amine

Hisanori Nambu,* Yuta Onuki, Koga Yamazaki, and Takayuki Yakura

*Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan

Abstract

Synthesis of 1-azaazulenes using ring-opening cyclization of spirocyclopropane with a primary amine was accomplished. The reaction of cycloheptane-1,3-dione-2-spirocyclopropane with 2,4-dimethoxybenzylamine in refluxing acetonitrile resulted in a 94% yield of 1,2,3,6,7,8-　hexahydrocyclohepta[b]pyrrol-4(5H)-one. The obtained product was successfully converted into 1-azaazulenes by deprotecting the amino-protecting group followed by oxidation.

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Published online: 22nd January, 2021

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)7
■ Conformational Control in Stereoselective Chemical Reactions: from Amino Acids to Iminosugars

Ari Koskinen*

*Department of Chemistry and Material Sciences, Aalto University, Finland

Abstract

Two alternative synthetic strategies for the synthesis of vicinal amino alcohols from naturally occurring amino acids have been investigated, viz. one going through diastereoselective addition of organometallic species to an amino aldehyde and one going through α’-chiral α,β-enones and their diastereoselective reduction. Based on these investigations we were able to develop a synthetic strategy towards all diastereomers of deoxynojirimycin starting from naturally occurring serine through a divergent route with a late stage intermediate that can be prepared in large quantities and in enantiomerically pure form.

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Published online: 19th January, 2021

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)47
■ N-Glycosylation of Thio-Glycoside Derived from Odorless Thiols Using Hypervalent Iodine(Iii) Reagent

Koji Morimoto, Kana Yanase, Tohru Kamitanaka, and Tetsuya Kajimoto*

*School of Pharmacy, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga, Japan

Abstract

A general and efficient protocol for direct N-glycosylation using inexpensive and readily available thioglycosides prepared from an odorless sulfur source was established. The use of easily available reactants and the mild reaction conditions make this protocol feasible for practical applications.

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Published online: 19th January, 2021

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)4
■ Lesinurad – There Are More Ways Than One of Synthesizing The Drug

Piotr P. Graczyk* and Sven Nerdinger*

*Early Stage Development, Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

Over the last several years significant efforts have been devoted, particularly in China, to develop new syntheses of Lesinurad. Virtually all key bonds in this molecule can now be created in many different ways, often in a very high yield. Although almost all of the chemistry examples presented in this review come from patent applications and as such have not been subjected to rigorous peer review, they may serve as an inspiration to solve analogous synthetic problems. However, the readers are encouraged to pay particular attention to the very recent trends in the literature which use multicomponent reactions and flow chemistry to minimize the environmental impact and achieve high yields of API at the same time.

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Published online: 19th January, 2021

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)5
■ Azido, Cyano, and Nitrato Cyclic Hypervalent Iodine(Iii) Reagents in Heterocycle Synthesis

Naoko Takenaga,* Hideyasu China, Ravi Kumar, and Toshifumi Dohi*

*Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan

Abstract

In recent years, synthetic applications of cyclic hypervalent iodine reagents have undergone significant developments. Among them, benziodoxol(on)es containing azido, cyano, and nitrato ligands have been found to be useful synthetic tools for the preparation of functionalized heterocyclic compounds. This review aims to summarize recent synthetic applications of benziodoxol(on)es as effective heteroatom-introducing reagents.

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Published online: 12th January, 2021

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)66
■ Facile Preparation of 1-Hydroxy-1,2-Benziodoxol-3(1h)-One 1-Oxide (Ibx) and Dess–Martin Reagent Using Sodium Hypochlorite under Carbon Dioxide

Kazunori Miyamoto,* Tomohide Okada, Takashi Toyama, Shinji Imamura, and Masanobu Uchiyama*

*Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

We have developed a safe, convenient, and inexpensive method for preparation of the widely used oxidizing agent 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide (IBX), by treatment of 2-iodobenzoic acid with aqueous sodium hypochlorite under CO2 at room temperature. As the only by-product is NaCl, this reaction can be utilized for one-pot synthesis of 1,1,1-triacetoxy-1,2-benziodoxol-3(1H)-one (Dess-Martin reagent) in excellent yield.

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Published online: 8th January, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14397
■ Synthesis of Some (Triindolyl)dimethanes and (Tetraindolyl)trimethanes

Kittya Somphol, Naresh Kumar, and David StC. Black*

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

Abstract

Acid catalyzed substitution reactions of 3-substituted-4,6-dimethoxyindole-2,7-dimethanols with 4,6-dimethoxyindoles substituted at C3 and C7 give (triindolyl)dimethanes with 2,2’- and 2,7’-methylene links in good yields. A related example involving a 4,6-dimethoxyindole substituted at C3 and C2 generates the corresponding (triindolyl)dimethane with 2,7’- and 7,7’-methylene links. Similar reactions of 2,7-di(hydroxymethyl)-4,6-dimethoxy-3-methylindole occur with N-methylindole and in the case of 1,2-di(indolyl-1-methyl)benzene generate a 16-membered ring compound in high yield. This methodology was also applied to (diindolyl)-dimethanols to afford a range of tetraindolyl trimethanes.

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Published online: 6th January, 2021

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14391
■ [2+2]Photocycloaddition of 5,6-Substituted 2-Oxo-2H-pyran-3-carboxylates with Alkenes

Yun-Han Hsieh, Hiroki Iwasaki, Yumina Iwai, Miki Adachi, Kanako Kitai, Eri Kuribayashi, Yuri Hirata, Suzuna Sakaguchi, Naoko Sakaguchi, Naoto Kojima, and Masayuki Yamashita*

*Kyoto Pharmaceutical University, 1 Misasagi-Shichono-cho, Yamashina, Kyoto 607-8412, Japan

Abstract

The [2+2]photocycloaddition of alkenes and 5,6-substituted 2-oxo-2H-pyran-3-carboxylates with an ester as an electron-withdrawing group was developed. The 3,4-adducts, 4,5-disubstituted 3-oxa-2-oxobicyclo[4.2.0]oct-4-ene-1-carboxylates, were obtained in moderate yields accompanied by considerable amounts of the 5,6-adducts, 1,6-disubstituted 2-oxa-3-oxobicyclo[4.2.0]oct-4-ene-4-carboxylates. These structures, including their stereochemistry, were determined by various spectral and computational analyses, and some were examined by X-ray crystallographic analysis. The determined regio- and stereoselectivities were explained by frontier orbital theory.

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Published online: 5th January, 2021

Review | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)33
■ Umpolung of Electron-Rich Heteroarenes with Hypervalent Iodine Reagents

Pamela Pal,(a) Jerome Waser,(b)*and Raj Kumar Nandi(a)*


* a Department of Chemistry, Diamond Harbour Women’s University, Sarisha, West Bengal-743368, India
* b ISIC-SB-LCSO, Ecole Polytechnique Federale de Lausanne (EPFL), Av. Forel 2, BCH 1402, Switzerland

Abstract

Five-membered heterocycles are well known for their innate nucleophilicity. In contrast, reaction of these heterocycles as electrophiles is less established and has become only recently an intensively investigated research area in synthetic chemistry. The use of hypervalent iodine reagents for the umpolung of the nucleophilic reactivity has been especially successful. This review provides a comprehensive overview regarding the generation of electrophilic intermediates from electron-rich heterocycles using hypervalent iodine reagents. The functionalization with different heteroatoms, arenes or heteroarenes nucleophiles is then described.

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Published online: 24th December, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)45
■ Generation of Monoaryl-λ3-iodanes from Arylboron Compounds through ipso-substitution

Ayako Nakano, Yukino Okabe, Keitaro Matsuoka, Narumi Komami, Keito Watanabe, Masahiro Kojima, Tatsuhiko Yoshino, and Shigeki Matsunaga*

*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan

Abstract

Monoaryl-λ3-iodanes serve as versatile oxidants and arylating reagents in organic synthesis. In addition to the oxidation of iodoarenes, electrophilic substitution reactions using iodine tricarboxylates have been used for the synthesis of monoaryl-λ3-iodanes. Here, we report that ipso-substitution reactions of aryltrifluoroborates with iodine tris(trifluoroacetate) in DMF or DMA smoothly produced monoaryl-λ3-iodanes, which were readily converted to aryliodonium ylides. We also demonstrated that sequential C–H borylation and the ipso-substitution efficiently introduced the I(III) group under steric control.

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Published online: 24th December, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14386
■ Synthesis of Roche Lactone via the Enantioselective Alcoholysis of meso-Cyclic Anhydride Strategy: A Practical Approach Employing an Efficient and Reusable Organic Microgel Auxiliaries

Fei Xiong,* Chang-Cheng Xi, Chao Ma, Lu Chen, Ming-Wei Sun, Xing-Guang Zhang, and Dan-Feng Hong

*Department of Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China

Abstract

Roche lactone, a key chiral intermediate of the natural water-soluble B series vitamin (+)-biotin, was synthesized from meso-cyclic anhydride in overall yield 78% through three steps, including heterogeneous asymmetric desymmetrization, chemoselective reduction and lactonization.

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Published online: 23rd December, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)43
■ Dihalogenative Cyclization for the Synthesis of 4-Bromo-1-bromoalkyl-5-aryl/alkyl/alkenyl-pyrazoles

Motohiro Yasui, Maki Hasegawa, Keiji Konishi, Norihiko Takeda, and Masafumi Ueda*

*Kobe Pharmaceutical University, Motoyamakita, Higashinada, Kobe 658-8558, Japan

Abstract

A copper-mediated domino reaction involving cyclization, bromination, and nucleophilic substitution of N,N-disubstituted hydrazones, which are labile under oxidative conditions, to synthesize 4-bromo-1-bromoalkyl-5-aryl/alkyl/alkenyl-pyrazoles, is achieved. This method features the simultaneous construction of pyrazoles and two C-Br bonds, which are synthetically useful.

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Published online: 23rd December, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14354
■ Synthesis and Biological Studies of Some New Pyrazole, Dihydropyridinethione, Pyrimidine, Thiophene and 4H-Pyran Derivatives

Ibrahim Saad Abdel Hafiz, Mohamed Ahmed Mahmoud Abdel Reheim,* Hala Mohamed Reffat, and Ahmed Adel Mohamed Sarhan

*Department of Chemistry, Faculty of Science, Arish Univeristy, Arish 45511, Egypt

Abstract

This study aims to synthesis of 1-(2-hydroxy-4-methylphenyl)-3-phenylpropane-1,3-dione 3 in a quantitative yield from the reaction of ethyl benzoylacetate and m-cresol using a microwave in the absence of solvents. Phenylpropane-1,3-dione derivative 3 was used as the key synthetic intermediate for the synthesis of many derivatives in this study. A new pyrazole 12, pyrimidine 15, thiophene 37, 4H-pyrane 51 and pyridine derivatives 8, 28, 34, 41 and 46 were synthesized through different chemical reactions. The structures of the newly synthesized compounds were confirmed based on analytical and spectral data. The compounds were evaluated for both their in vitro antibacterial and antifungal activities. The compounds showed varying degree of antimicrobial activity.

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Published online: 23rd December, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-948
■ Imidazole Chemistry in Crop Protection

Clemens Lamberth*

*Syngenta Crop Protection AG, Research Chemistry, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland

Abstract

An overview is given of the significance of the imidazole scaffold in crop protection chemistry. The main herbicidally, fungicidally and insecticidally active imidazole classes are presented, together with their synthesis routes, modes of action and biological efficacies. Also, partially and fully saturated imidazole derivatives, such as imidazolines and imidazolidines, oxygenated derivatives, such as imidazolinones and hydantoins as well as annulated derivatives, such as benzimidazoles, are covered. In addition, also the role of imidazoles as intermediates or reagents in the synthesis of other agrochemicals is reported.

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Published online: 21st December, 2020

Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14366
■ Synthesis of Poly(cyclotriphosphazene-co-3,3'-sulfonyldianilide) Microspheres and Their Adsorption of Anionic (Congo Red) Dye

Zeng Xiong, Yanfei Wang,* Xiaoqing Xie, Honzheng Li, and Chen Yao

*School of Chemistry and Chemical Engineering, University of South China, Hengyang, Hunan 421001 PR China

Abstract

The cyclomatrix phosphazenes-co-3,3'-sulfonyldianiline PSD-NH2 microspheres with active amino groups on the surface were prepared by precipitation which was used to removal organic dyes from aqueous solution. The synthesized amino cyclomatrix phosphazenes (PSD-NH2) microspheres were characterized by FT-IR, SEM, XPS and XRD. The effects of different pH, sorbent dosage, contact time, initial Congo red (CR) concentration and different temperature on the adsorption of Congo red by the cross-linked microspheres were studied. The experimental data show that the adsorption capacity of PSD-NH2 microspheres on Congo red reaches 186.70 mg/g under the optimal adsorption conditions. It conforms to the pseudo-second-order kinetic equation and Langmuir isotherm model. The selective adsorption mechanism for Congo red dye can be summarized as intermolecular electrostatic interaction, hydrogen bond between PSD-NH2 microspheres adsorbed on the surface and Congo red, π-π and C-H…π stacking and other molecular forces. Thermodynamic studies have shown that the adsorption of Congo redon PSD-NH2 microspheres is endothermic and spontaneous in nature. Thus, amino polyphosphazene (PSD-NH2) microspheres have excellent adsorptionperformance for Congo red.

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Published online: 21st December, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-949
■ Recent Advances in Synthetic Transformations with Robust Yet Reactive B(Dan) Moiety

Jialun Li and Hiroto Yoshida*

*Graduate School of Advanced Science and Engineering, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.

Abstract

Recent advances in the direct B(dan)-installing reactions (dan = naphthalene-1,8-diaminato) into organic frameworks by utilizing (pin)B–B(dan) or H–B(dan) as a B(dan) source, and the direct cross-coupling of dan-substituted organoboron compounds therefrom are described.

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Published online: 18th December, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)42
■ Catalytic Asymmetric Ring-Opening of σ-Symmetric Cyclic Carbonates with Chiral Amino Sulfonamide Catalysts

Michiyasu Nakao, Tomomi Shozui, Daisuke Inoue, Takahito Ihara, Syuji Kitaike, and Shigeki Sano*

*Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78 Sho-machi, Tokushima 770-8505, Japan

Abstract

Enantioselective ring-opening of σ-symmetric six-membered cyclic carbonates with benzyl alcohol catalyzed by 20 mol% of chiral amino sulfonamide catalysts afforded chiral acyclic carbonates in up to 79% ee.

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Published online: 18th December, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14360
■ Synthesis of α-Bromomethyl Ketones in CuBr - bpy System

Abulipizi Gulizhabaier, Hasimujiang Balat, and Abulikemu Abudu Rexit*

*Xinjiang Key Laboratory of Energy Storage and Photoelectrocatalytic Materials and Department of Chemistry, Xinjiang Normal University, Urumqi, China

Abstract

Herein we reported a convenient, regiospecific, efficient and fairly general method for the preparation of α-bromomethyl ketones from α,α,α-tribromomethyl carbinols with 2.2 equivalents of copper(I) bromide and 2,2'-bipyridine in refluxing 1,2-dichloroethane.

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Published online: 15th December, 2020

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-20-14373
■ Peniphilones A and B: Azaphilone Alkaloids from the Endophytic Fungus Penicillium maximae

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

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

Abstract

Two new azaphilone alkaloids, peniphilones A and B (1 and 2), and a known congener, (+)-sclerotiorin (3), were isolated from the endophytic fungus Penicillium maximae by screening based on chemical analysis by UPLC-HRMS with our in-house extract library of natural sources. The structures of 1 and 2 were elucidated on the basis of NMR and HRESI-MS spectroscopic data.

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Published online: 10th December, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)44
■ An Arylative Aziridination Process toward Aspidosperma Alkaloids

Kouassi Signo, Elsa Deruer, Siomenan Coulibali, and Sylvain Canesi*

*Laboratoire de Méthodologie et Synthèse de Produits Naturels, Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, H3C 3P8, Québec, Canada.

Abstract

An arylative aziridination process has been developed from dibrominated phenols containing a Fukuyama sulfonamide on the lateral chain. A two-step procedure involving the formation of a dienone by a phenol oxidation reaction mediated by a hypervalent iodine reagent (Kita reaction) followed by an intramolecular arylative aziridination process was used. This second step occurred under mild conditions via a Michael–Smiles ring-closure cascade, producing sulfur dioxide as the only byproduct. Additionally, a stereoselective approach was observed with tyrosine derivatives. This transformation respects the rules of green chemistry and atom economy. These new polyfunctionalized scaffolds could offer several synthetic possibilities for the total synthesis of natural products such as the main core of Aspidosperma alkaloids.

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Published online: 3rd December, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)41
■ Preparation of Optically Pure Dinuclear Cobalt(III) Complex with Λ-Configuration as A Dianionic Chiral Catalyst

Mohamed S. H. Salem, Ankit Kumar, Makoto Sako, Tsukasa Abe, Shinobu Takizawa,* and Hiroaki Sasai*

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

Abstract

The disodium salt of enantiomerically pure dimeric Λ-cobalt(III) complex 1 was prepared in one-pot from sodium triscarbonatocobaltate(III) and Schiff base ligand (Ra,S,S)-2 formed by the condensation of (R)-3,3ʹ-diformyl-2,2ʹ-dihydroxy-1,1ʹ-binaphthyl 3 with (S)-tert-leucine 4. Preliminary screening of 1 as a chiral catalyst was conducted for the bromocyclization of a tryptamine derivative.

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Published online: 3rd December, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)40
■ Concise Synthesis of an Amide-Functionalized [7]Helicene-like Molecule via Intramolecular Amidation

Yongning Xing, Masanori Nikaido, Takuya Murai, Shohei Hamada, Yusuke Kobayashi, Takahiro Sasamori, Takeo Kawabata, and Takumi Furuta*

*Department of Pharmaceutical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto 607-8414, Japan

Abstract

A concise synthesis of an amide-functionalized [7]helicene-like molecule was achieved via the intramolecular amidation of an in-situ-generated biaryl δ-amino acid derivative. An X-ray analysis of racemic mixture of this helicene-like molecule revealed a helically twisted π-system and that the (M)- and (P)-isomers associate pairwise via hydrogen-bonding interactions, which results in a one-dimensional columnar packing in the crystal structure.

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Published online: 30th November, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-944
■ Highly Oxidized γ-Lactam-Containing Natural Products: Total Synthesis and Biological Evaluation

Kosaku Tanaka III,* Hiroshi Kogen, and Kenichi Kobayashi*

*Graduate School of Pharmaceutical Sciences, Health Sciences University of Hokkaido; 1757 Kanazawa, Tobetsu-cho, Ishikari-gun, Hokkaido 061-0293, Japan

Abstract

γ-Lactam is a ubiquitous structure found in the natural products. A number of highly oxidized γ-lactam-containing natural products are produced by various fungi. These compounds often show a wide range of biological activities because their multiple internal reaction sites, which arise from the high oxidation state of the compounds, can react with biological nucleophiles. Due to their high reactivity and dense functionality, total syntheses of these molecules require strict control of the inherent reactivity and the appropriate design of synthetic intermediates. This review focuses on the recent total syntheses of some highly oxidized γ-lactam-containing natural products, including fused bicyclic (epolactaene, NG-391, lucilactaene, L-755,807), spirocyclic (azaspirene, pseurotin A, E, and F2, cephalimysin A–C, FD-838, and berkeleyamide D), and tricyclic (rubrobramide and talaramide A) skeletons, and on the structure-activity relationship studies of related molecules.

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Published online: 27th November, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)39
■ Intramolecular Transamidation-Cyclization of N-(α-Oxoacetyl) Diamine: Influence of Solvent, Acidity and Substituents

Takashi Kouko, Hiroaki Miyazawa, Hideki Hikita, Hiromi Totsuka, Kazuhiro Higuchi,* and Tomomi Kawasaki*

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

Abstract

We studied the selective formation of 3,5- and 2,5-pyrazinone via a transamidation-cyclization reaction. The equilibrium between acyl amides changed depending on the solvent, acidity, and substituents. Furthermore, selective transformation of 2,5-pyrazinone was accomplished by using a substrate with a secondary amine.

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Published online: 26th November, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)37
■ Synthesis, Structure, and π-Donor Properties of Tris(Ethyleledioxy)Benzene and Bis(Ethyleledioxy)Thiophene

Ryoji Watanabe, Tohru Nishinaga,* Yoshiyuki Kuwatani, and Masahiko Iyoda*

*Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

Abstract

Tris(ethylenedioxy)benzene 3 and bis(ethylenedioxy)thiophene 4 have been synthesized starting from 2,3-dibromo-1,4-dioxene in 25 and 38% overall yields, respectively. These ethylenedioxy-fused benzene and thiophene can be easily oxidized to produce the corresponding radical cations 3•+ and 4•+ because of their high-lying HOMO levels. Interestingly, the radical cation 3•+ exhibits a fairly strong fluorescent emission at λmax 602 and 590 nm (φF = 0.40 in MeCN and 0.50 in H2SO4).

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Published online: 20th November, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)34
■ Synthesis and Blue Dyeing Ability for Polypropylene Fabrics of Various 3,7-Bis(Dialkylamino)Phenoxazin-5-Ium Salts and the Sulfur and Selenium Analogs

Takumi Yoshida* and Masahito Segi*

*Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

3,7-Bis(dialkylamino)phenoxazin-5-ium salts having different amino groups (dimethylamino, diethylamino, dipropylamino, dibutylamino, and pyrrolidyl) and counter anions (chloride, bromide, iodide, hydrogensulfate, and nitrate) were synthesized in up to 80% isolated yield as blue cationic dyes. In addition, 3,7-bis(diethylamino)phenothiazin-5-ium and 3,7-bis(diethylamino)phenoselenazin-5-ium iodides were also synthesized in 20% and 17% isolated yields, respectively. Polypropylene fabrics were dyed with the above synthesized blue cationic dyes. As an evaluation result, it has been found that the moderate size such as diethylamino groups at the 3 and 7 positions of phenoxazinium salts is suitable for the dyeing ability.

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Published online: 20th November, 2020

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)3
■ Recent Advances in Synthetic Strategies for The C4a,C9a-Fused Tetracyclic Hydrocarbazole Core Structure of Minfiensine and Related Akuammiline Alkaloids

Keisuke Hosoya, Keita Iida, Minami Odagi,* and Kazuo Nagasawa*

*Department of Biotechnology and Life Science, Faculty of Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan

Abstract

The Strychnos alkaloid minfiensine and its analogs among the akuammiline alkaloids have a variety of biological activities, including anti-tumor and analgesic activities, and have therefore attracted considerable synthetic interest. Here we provide an overview of recent advances in methodologies for the construction of the characteristic tetracyclic hydrocarbazole core structure containing a fused pyrrolidine ring at C4a and C9a.

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Published online: 13th November, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)38
■ De Novo Approach to Izidines via a Gold-Catalyzed Hydroamination–N-acyliminium Ion Cyclization of Acyclic Ynamides

Kenji Sugimoto,* Shota Mizuno, Misaki Shirato, Kosuke Tanabe, and Yuji Matsuya*

*Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan.

Abstract

A gold(I)-catalyzed novel domino reaction of acyclic ynamides yielding nitrogen-fused bicyclic skeletons was described. The reaction with 10 mol% JohnPhosAuNTf2 and stoichiometric amount of PhCO2H enables constructions of quinolizidine and indolizidine skeleton having tetrasubstituted carbon center. Especially in the case of quinolizidine synthesis, the quaternary stereogenic center could be furnished under highly diastereoselective manner.

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Published online: 9th November, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-943
■ Systematic Search for Transition States in Complex Molecules: Computational Analyses of the Regio- and Stereoselective Interflavan Bond Formation in Flavan-3-Ols

Daisuke Urabe* and Keisuke Fukaya

*Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama 939-0398, Japan

Abstract

This review describes our recent work on a systematic search for transition states in transformations of complex molecules. The method features a combination of a conformational search method using constrained models to create a large library of transition-state candidates, and subsequent density functional theory (DTF)-based transition state calculations for the candidates. The method is applicable to calculation of transition states for inter- and intramolecular interflavan bond formation in flavan-3-ols to reproduce experimental results for highly regio- and stereoselective C-C bond formation. The specific roles of van der Waals interactions in the transition states can be visualized by NCIPLOT mapping to show the importance of weak but attractive interactions for selective interflavan bond formation.

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