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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

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)35
Design, Synthesis, Physical Properties and Indoleamine 2, 3-Dioxygenase 1 Inhibitory Activity of Substitued Indole Derivatives with N-H, N-Metohymethyl, or N-Mehylthiomethyl Group toward Fragment-Based Drug Discovery

Kenta Hayami, Yuichi Kuboki, Katsumi Ohta, Bangzhong Lin, Megumi Fumimoto, Kazuto Nunomura, Jun-Ichi Haruta , Kenichi Murai, Hiromichi Fujioka, Akira Asai, and Mitsuhiro Arisawa*

*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan

Abstract

We designed and prepared N-H, N-CH2OMe(MOM), and N-CH2SMe (MTM) forms of various substituted indoles, using a docking study, as a small fragment library toward fragment-based drug discovery (FBDD) and evaluated their indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitory activities and physical properties.

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Published online: 29th October, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)32
Hybrid Catalysis of 8-Quinolinecarboxaldehyde and Brønsted Acid for Efficient Racemization of α-Amino Amides and Its Application in Chemoenzymatic Dynamic Kinetic Resolution

Kohsuke Ohmatsu, Mari Kiyokawa, Yuto Shirai, Yuya Nagato, and Takashi Ooi*

*Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya, 464-8601, Japan

Abstract

The combination of 8-quinolinecarboxaldehyde and benzoic acid proved to be an effective catalyst system for the racemization of N-unprotected α-aryl- or α-alkyl-substituted α-amino amides. Application of this system to chemoenzymatic dynamic kinetic resolution provided an efficient access to enantiomerically pure N-acetyl-α-amino amides in good to high yields.

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Published online: 29th October, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)28
Synthesis of 1-Methoxy-1H-Indoles with a Heterocyclic Moiety via Unstable Indole Isothiocyanate by Using Enzyme from Brassicaceae Plant

Kaori Ryu, Seikou Nakamura,* Koya Miyagawa, Souichi Nakashima, and Hisashi Matsuda*

*Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan

Abstract

A synthesis of five 1-methoxy-1H-indole derivatives with imidazole, pyrazole, 1H-1,2,3-triazole, and 1H-1,2,4-triazole moieties was achieved by focusing on the formation mechanism of plant constituents. The objective 1-methoxy-1H-indole derivatives were obtained in situ (in one step) through the reaction of an unstable 3-(isothiocyanatomethyl)-1-methoxy-1H-indole, which was derived from neoglucobrassicin and plant enzyme myrosinase, and a heterocyclic compound. We have great hopes that this method would be useful for the development of medicinal seeds.

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Published online: 28th October, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)29
Stereoselective Alkylation of Oxathiazinane N,O-Ketals for the Construction of Aza-Quaternary Carbon Centers

Hisanori Nambu, Eri Tanaka, Mai Okada, Chiaki Hirosawa, Narumi Noda, Tomoya Fujiwara, and Takayuki Yakura*

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

Abstract

Stereoselective construction of aza-quaternary carbon centers was achieved using the alkylation of oxathiazinane N,O-ketals prepared by Rh(II)-catalyzed C–H amination of sulfamates. The addition of alkyl Grignard reagents into N,O-ketals in the absence of any Lewis acid proceeded stereoselectively to provide the corresponding alkylated products with an aza-quaternary carbon center in high yields. The obtained product could be converted into an α-amino alcohol derivative, which is a potential synthetic intermediate for sphingofungin F and its derivatives.

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Published online: 27th October, 2020

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)1
Recent Advances in the Microwave Assisted Synthesis of Benzofuran and Indole Derivatives

Thaipparambil Aneeja, Sankaran Radhika, C M A Afsina, and Gopinathan Anilkumar*

*School of Chemical Sciences, Mahatma Gandhi University, Priyadarsini Hills, Kottayam, Kerala , India

Abstract


Abstract – Microwave (MW) assisted syntheses are environment friendly, efficient, rapid and convenient methodology for the synthesis of organic compounds. Benzene ring fused to a five membered ring containing N or O atom exhibits wide range of biological activities. Benzofuran is present in polymers, pharmaceuticals, and bioactive natural products. Benzofuran is significant as insecticides, herbicides, anti-inflammatory and anti-viral agents. Indoles are well known scaffold showing noteworthy activities like anti-tumor, anti-viral, anti-microbial and anti-oxidant. Indole derivatives are valuable moiety in different therapeutically active drug molecules. On account of the biological significance of benzofuran and indole scaffold, this review describes the recent advances in microwave assisted synthesis of benzofurans and indoles, and covers literature from 2012-2020.

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Published online: 26th October, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)30
Synthesis and Structure-Activity Relationship Study of 1,12-Dicarba-closo-dodecaborane-based Triol Derivatives as Nonsecosteroidal Vitamin D Analogs

Shinya Fujii, Ryota Sekine, Atsushi Kano, Hiroyuki Masuno, Emiko Kawachi, Tomoya Hirano, and Hiroyuki Kagechika*

*Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10, Surugadai, Kanda, Chiyoda-ku 101-0062, Japan

Abstract

The secosteroidal hormone 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] is a specific ligand of nuclear vitamin D receptor (VDR), and novel vitamin D analogs are promising candidates for multiple clinical applications. We previously developed a series of 1,12-dicarba-closo-dodecaborane (p-carborane) derivatives as nonsecosteroidal VDR agonists. Here, we report the synthesis and structure-activity relationship of p-carborane-based nonsecosteroidal vitamin D analogs bearing a nitrogen or a sulfur atom in the linker structure. Biological evaluation revealed that the structure–activity relationships of amine derivatives and sulfide derivatives are different, and therefore the choice of the linker structure significantly affects the activity. We also found that benzylamine structure could be a lead scaffold for novel vitamin D analogs. The structure–activity relationships presented here should be helpful in further development of nonsecosteroidal vitamin D analogs.

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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: 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: 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: 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: 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: 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: 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: 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: 7th August, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)18
Copper-Mediated Trifluoromethylation of Borylporphyrins Using An in Situ-Generated CF3 Radical from NaSO2CF3 and tert-Butyl Hydroperoxide

Satoshi Hayashi,* Daisuke Yamazaki, and Toshikatsu Takanami*

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

Abstract

We developed a method for the copper-mediated reaction of borylated Ni(II) porphyrins using NaSO2CF3 (Langlois’ reagent) and tert-butyl hydroperoxide (TBHP) to prepare trifluoromethylated Ni(II) porphyrins.Porphyrin trifluoromethylation can be carried out under mild conditions and exhibits both excellent substrate generality and functional group compatibility.

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Published online: 30th July, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)22
Catalytic Enantioselective Oxa-Hetero-Diels-Alder Reactions of Enones with Aryl Trifluoromethyl Ketones: Synthesis of Tetrahydropyranones

Maira Pasha and Fujie Tanaka*

*Chemistry and Chemical Bioengineering Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa 904-0495, Japan

Abstract

Diastereo- and enantioselective oxa-hetero-Diels-Alder reactions of enones with aryl trifluoromethyl ketones that afford tetrahydropyranone derivatives catalyzed by an amine-based catalyst system are reported. The major diastereomers of the tetrahydropyranone products obtained in these reactions had the relative stereochemistry different from that of the previously synthesized tetrahydropyranone derivatives.

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Published online: 29th July, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)17
Identification of a Novel Indoleamine 2,3-Dioxygenase Inhibitor Bearing an Eight-Membered Ring Fused Indole Scaffold and Its Structure-Activity Relationship

Ayuta Yamaguchi, Shinsuke Inuki,* Katsumi Ohta, Shinya Oishi, Akira Asai, and Hiroaki Ohno*

*Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Indoleamine 2,3-dioxygenase 1 (IDO1) is a promising target for cancer immunotherapy because it is overexpressed in a variety of tumor cells. IDO1 also plays an important role in the process of immune escape by tumors. In this study, we identified a novel IDO1 inhibitor KPYC12532 (5a) bearing an eight-membered ring-fused indole scaffold by screening our compound library. To develop novel IDO1 inhibitors, we conducted a structure-activity relationship study of 5a and found some compounds displaying comparable activity. These results provide useful insight for the design of novel IDO1 inhibitors.

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Published online: 17th July, 2020

Review | Special issue | Prepress
DOI: 10.3987/REV-20-SR(K)2
Environmentally Benign Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide using Binary and Bifunctional Catalysts

Ken Okuno, Ryuichi Nishiyori, Mana Hiraki, and Seiji Shirakawa*

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

Abstract

The extensive utility of five-membered cyclic carbonates has been well established in the chemical industry. Among the various methods available for the synthesis of five-membered cyclic carbonates, coupling reactions that involve epoxides and carbon dioxide are ideal. This review introduces environmentally benign catalytic systems for the synthesis of cyclic carbonates under mild reaction conditions. Application of chiral catalysts to the asymmetric synthesis of optically active cyclic carbonates is also discussed.

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Published online: 17th July, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)15
Selective Reduction and Dihydroxylation of α,β-Unsaturated Esters in The Presence of Enals: One-Pot Synthesis of A 2,5-Disbstituted Tetrahydrofuran

Kenta Morita, Kenichi Murai, Mitsuhiro Arisawa, and Hiromichi Fujioka*

*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan

Abstract

Two-way discriminative conversion, reduction and dihydroxylation of α,β-unsaturated esters were achieved in the presence of enals using two phosphonium salts as in situ protecting groups. Furthermore, a pot-economical one-pot synthesis of a tetrahydrofuran derivative was achieved.

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Published online: 9th July, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)21
Regiodivergent Ring Opening Reactions of 2-Arylated 3-Nitrocyclopropane-1,1-Dicarboxylates Leading to Polyfunctionalized Dipoles

Haruyasu Asahara,* Rikiya Kamidate, and Nagatoshi Nishiwaki*

*Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0821, Japan

Abstract

Two kinds of Lewis acid induced ring-opening reactions of 2-aryl-3-nitrocyclopropane-1,1-dicarboxylates proceeded to afford 5-aryl-2-isoxazolines and γ-keto acid derivatives, respectively. Different ring-opening modes could be controlled by choosing the ligand or solvent.

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Published online: 23rd June, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)12
Bifunctional-Benzothiadiazine-Catalyzed Regio- and Stereoselective Aldol Reactions using A 1,3-Acetonedicarboxylic Acid Monoester

Yusuke Tokuhiro, Noboru Hayama, Yusuke Kobayashi, and Yoshiji Takemoto*

*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Regio- and stereoselective decarboxylative aldol reactions of a 1,3-acetonedicarboxylic acid monoester were achieved using an aminobenzothiadiazine organocatalyst. The products were obtained with perfect regioselectivity and moderate to good enantioselectivity using various aromatic aldehydes. Subsequently, the thus obtained adducts were efficiently converted into various chiral building blocks.

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Published online: 23rd June, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)14
Synthesis of Pyrrolo[2,3-C]Quinoline Alkaloid Marinoquinolines

Takashi Nishiyama, Mari Murakami, Kimiko Taninaka, Erina Hamada, Mai Endo, Daiki Kinou, Noriyuki Hatae, and Tominari Choshi*

*Graduate School of Pharmacy & Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan

Abstract

In this study, the synthesis of pyrrolo[2,3-c]quinoline as a common skeleton, is described. The process is based on the thermal electrocyclization of 3-phenylpyrrole containing isocyanate as 2-azahexatriene. Using this approach, the total synthesis of three natural marinoquinolines A, B, and E can be successfully achieved.

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Published online: 2nd June, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)10
Studies on Rotational Stability of 2-Aryl-3-(2-Fluorophenyl)Quinazolin-4-One Derivatives

Asumi Iida, Kazuya Saito, Nanami Asada, Yuuki Fujimoto, and Osamu Kitagawa*

*Department of Applied Chemistry, Faculty of Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Kohto-ku, Tokyo 135-8548, Japan

Abstract

The rotational barriers around an N-(2-F)C6H4 bond in 2-aryl-3-(2-fluorophenyl)quinazolin-4-ones considerably lowered (ca. 4 kcal mol-1 lower) in comparison with those of 2-alkyl-3-(2-fluorophenyl)quinazolin-4-ones. The transition state structure estimated by the DFT calculation indicates that the considerable decrease in the rotational barriers in 2-aryl derivatives is caused by the alleviation of the steric repulsion between an ortho-substituent of 2-fluorophenyl group and 2-aryl group.

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