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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: 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: 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: 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) AG 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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Published online: 18th August, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-936
An Overview of Quantitative and Qualitative Approaches on the Synthesis of Heterocyclic Kojic Acid Scaffolds through the Multi-Component Reactions

Fatemeh Mohajer and Ghodsi Mohammadi Ziarani*

*Department of Chemistry, Alzahra University, Vanak Square, 1993893973, Tehran, Iran

Abstract

Multi-component reactions as powerful synthetic methods were developed to provide efficient complex scaffolds, including kojic acid, through the one-pot one-step fashion. This review highlights the progress of multicomponent reactions covering kojic acid under different conditions through, short reaction time, higher yields, and environmental friendliness via producing various molecules. The aim of this paper is to review the literature from 2015 to 2020 via quantitative and qualitative approaches.

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Published online: 13th August, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-933
Recent Development of Stereoselective Glycosylation Reactions

Shino Manabe*

*Laboratory of Functional Molecule Chemistry, Pharmaceutical Department and Institute of Medicinal Chemistry, Hoshi University, 2-4-41 Ebara, Shinagawa, Tokyo, 142-8501, Japan

Abstract

Carbohydrates are the most abundant class among biological molecules. Advances in glycobiology have revealed the vital roles played by glycosides and glycoconjugates in biological events. In this context, access to homogenous oligosaccharides and glycoconjugates is critical for various biological investigations. Glycosylation is the cornerstone of glycoside synthesis, and during glycosylation, the control of stereoselectivity at the anomeric position is highly important. In this review, recent progresses in 1,2-cis-glycosylation reactions are summarized, with a focus on the influence of the protecting groups on the conformations of the glycosyl donors, role of reaction mixture additives, and synthetic utility of endocyclic cleavage of glycoside. Development of robust glycosylation reaction will contribute to biologically active oligosaccharide synthesis.

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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: 3rd July, 2020

Review | Regular issue | Prepress
DOI: 10.3987/REV-20-934
Aryne-Mediated Synthesis of Oxygen Heterocycles and Application to Cysteine-Selective Trapping

Hideto Miyabe*

*Laboratory for Medicinal Chemistry, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe City, 650-8530, Japan

Abstract

The use of arynes as the highly reactive intermediates in organic synthesis has attracted substantial attention. Particularly, the introduction of ortho-(trimethylsilyl)aryl triflates as easily activatable aryne precursors led to growing activity in this field. Most reactions using these aryne precursors proceed through the addition of nucleophiles to arynes and the subsequent trapping with electrophiles to give the multisubstituted arenes with structural diversity and complexity. Based on our studies, this review highlights the insertion of arynes, generated from ortho-(trimethylsilyl)aryl triflates, into C=O π-bond of formamides. Initially, the representative examples for formal [2+2] cycloaddition of arynes with the carbon–heteroatom double bond or the heteroatom–heteroatom double bond are shown. Next, the studies on the insertion of arynes into the N−C and C=O bonds of amide group including our three-component coupling reaction leading to oxygen heterocycles are summarized. The SN2’ reaction of tricyclic oxygen heterocycles, obtained by three-component coupling reaction, was studied by using carbon and sulfur nucleophiles. The SN2’ reaction was expanded to four-component coupling reaction. Finally, the application of tricyclic oxygen heterocycles to cysteine-selective trapping is described.

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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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Published online: 22nd May, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)13
3-Trifluoromethanesulfonyloxy-4,7-Dihydro-Pyrazolo[1,5-a]Pyridine Via Ring-Closing Metathesis: Synthesis and Transformation to Withasomnine Homologs

Yoshihide Usami,* Yuya Tatsui, Kodai Sumimoto, Ayami Miyamoto, Nanase Koito, Hiroki Yoneyama, and Shinya Harusawa

*Laboratory of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan

Abstract

3-Trifluoromethanesulfonyloxy-4,7-dihydropyrazolo[1,5-a]pyridine (9) was successfully synthesized from the starting material, pyrazole, via a sequence of reactions containing ring-closing metathesis as a key step. Suzuki-Miyaura coupling of 9 with various arylboronic acids, followed by oxidation or hydrogenation, readily afforded pyrazolo[1,5-a]pyridines (11) or 3-aryl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridines (12), respectively. Compounds 12 were found to be withasomnine homologs

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Published online: 21st May, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)7
Synthesis of 5-H Thiazoles via Thioamide Dianions with Thioformamides: Pyridylmethyl Group on The Nitrogen Atom of Thiazole Promotes The Formation of 5-H Thiazoles

Khurnia Krisna Puji Pamungkas , Shizuka Hattori, Toshifumi Maruyama, Masahiro Ebihara, and Toshiaki Murai*

*Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University , 1-1 Yanagido, Gifu, Gifu 501-1193, Japan

Abstract

The reaction of in situ-generated thioamide dianions having a pyridylmethyl group on the nitrogen atom with thioformamides resulted in the formation of 5-H thiazoles as major products along with 5-N,N-dimethylaminothiazoles. The presence of a pyridylmethyl group plays an important role in the formation of 5-H thiazoles. A wide range of substituents at the 2-position of a thiazole ring tolerated the reaction conditions, and the intramolecular cyclization reaction proceeded smoothly. However, a phenyl substituent at the 4-position of a thiazole ring significantly reduced the yields of 5-H thiazoles.

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Published online: 14th May, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)9
Synthesis of A Pentacoordinate Germanium Compound Possessing A γ-Lactone And A Dative-Bonding Carboxylic Acid

Hiroki Tanimoto,* Daiki Toumori, Tsumoru Morimoto, and Kiyomi Kakiuchi*

*Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan

Abstract

A pentacoordinate germanium compound consisting of a spirocyclic dilactone-like structure was synthesized. Both radical and oxidation synthetic routes afforded the diphenylgermanium dicarboxylic acid compound. Then, mono-dearylation by acid treatment successfully delivered a hypercoordinate germane product. X-Ray crystallographic analysis revealed that the product adopted trigonal bipyramidal geometry in which a γ-lactone ring and a dative-bonding carboxylic acid moiety were incorporated.

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Published online: 13th May, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)11
Synthesis of Pyrrolo[1,2-c]Pyrimidines

Easha Narayan, Liangfeng Fu, and Gordon W. Gribble*

*6128 Burke Laboratory, Department of Chemistry, Dartmouth College, Hanover, New Hampshire 03755, U.S.A.

Abstract

The synthesis of several new pyrrolo[1,2-c]pyrimidines from the base-induced condensation of pyrrolo-2-carbaldehydes with either TosMIC (toluenesulfonylmethyl isocyanide) or ethyl isocyanoacetate is described, along with the preparation of novel bis(pyrrolo[1,2-c]pyrimidines).

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Published online: 13th May, 2020

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)5
Conjugate Addition Reaction of Indole to Protected 2-Amino-1-Nitroethenes Mediated by Silica Gel

Kenichi Murai,* Shuji Miyazaki, and Hiromichi Fujioka*

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

Abstract

We have developed a silica-gel-mediated route for the conjugate addition of indole to protected 2-amino-1-nitroethenes for the synthesis of 1-indolyl-1,2-ethanediamines. This is the first demonstration of indole as the nucleophile for addition to protected 2-amino-1-nitroethenes.

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Published online: 12th May, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)8
Concise Preparation and Biological Evaluations of 9-cis-Retinoic Acid Analogues Having an Aromatic Ring

Takashi Okitsu,* Kinya Iwatsuka, Kimie Nakagawa, Toshio Okano, and Akimori Wada*

*Faculty of Pharmaceutical Science, Kobe Pharmaceutical University, 4-19-1, Motoyamakita, Higashinada, Kobe 658-8558, Japan

Abstract

A series of 9-cis-retinoic acid analogues having an aromatic ring were prepared in only two steps, and were evaluated for transcriptional activities with retinoic acid response element (RARE) and retinoid X response element (RXRE). Among them, compound 6c, bearing a 2-naphthyl substituent, exhibited the highest transcriptional activity with RXR selectivity.

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Published online: 8th May, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)6
Synthesis of Lactone-Fused Cyclopropanes by Ring Contractive α-Ketol Rearrangement of Ketal-Fused Cyclobutanones

Kiyosei Takasu,* Koichi Shigenaga, Kazuma Shimoda, Hiroshi Takikawa, and Yousuke Yamaoka

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

Abstract

Ring contraction of cyclic silyl ketal-fused cyclobutanones into lactone-fused cyclopropanes under desilylative conditions is described. The reaction affords 1-hydroxy- and 1-amino-1-cyclopropanecarboxylic acid derivatives from cyclobutanone substrates and their imine congeners, respectively.

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Published online: 28th April, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)3
Thermally-Induced Doping of The Regioregular Polythiophene Bearing Alkylene Spacered Benzene Sulfonate Group at The Side Chain

Chihiro Kubota, Daisuke Morita, Keisuke Fujita, Sonoka Yamamoto, Toyoko Suzuki, Kentaro Okano, Masahiro Funahashi, Masaki Horie, and Atsunori Mori*

*Department of Chemical Science and Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

Regioregular polythiophene bearing a benzenesulfonate group, which involved an alkylene spacer between thiophene and benzene ring, was synthesized. The obtained polythiophene was shown to improve its conductivity by heating the polymer thin film through the transformation of the ester group into the corresponding sulfonic acid.

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Published online: 17th April, 2020

Paper | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)1
Synthesis of Probe Molecules, 6-(Dimethylamino)-2-Phenylisoindolin-1-Ones, for Mechanistic Studies of Firefly Luciferase Inhibition

Medha J. Gunaratna, Bo Hao, Man Zhang, Madoka Nakagomi, Ai Ito, Takeo Iwamoto, and Duy H. Hua*

*Department of Chemistry, Kansas State University, Manhattan, KS 66506, U.S.A.

Abstract

Firefly luciferase is used in high-throughput screening based on the detection of chemiluminescence. It catalyzes an esterification reaction of luciferin with adenosine 5’-triphosphate (ATP) followed by decarbonylation with oxygen and concomitance of light. Previously, we reported that firefly luciferase also possesses acyl-CoA synthetase activity and catalyzes an aromatic carboxylic acid group of F-53, using ATP, Mg2+ and coenzyme A (CoA), to produce F-53 covalently attached to active-site lysine-529 residue of firefly luciferase through the formation of an amide group. The amidation of lysine-529 resulted in a deactivation of luciferase. In order to probe firefly luciferase inhibition’s mechanism, we synthesized two probe molecules 1 and 2, mimicking F-53. Molecule 1 contains an azido-appended side chain in the aromatic ring of F-53, while 2 possesses an azido and a carboxylic acid group appended side chains. Both synthetic schemes are readily amenable to large-scale syntheses. Molecule 1 was made from 2-allylaniline, which was derived from a thermal-induced aromatic-Claisen rearrangement of N-allylaniline. The azido-appended side chain of 2 was installed from a Horner-Wadsworth-Emmons reaction and the carboxylic acid side chain from a Sonogashira reaction.

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Published online: 16th April, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)4
Synthetic Studies on Densanins: Stereoselective Construction of A Pyrrolidine Ring Containing a Quaternary Carbon

Kyosuke Ueda and Satoshi Yokoshima*

*Graduate School of Pharmaceutical Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan

Abstract

We disclose our synthetic studies on densanins, which feature the stereoselective cycloaddition of a cycloheptenone and an azomethine ylide to construct a pyrrolidine ring containing a quaternary carbon

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Published online: 16th March, 2020

Communication | Special issue | Prepress
DOI: 10.3987/COM-20-S(K)2
5-Arylidenetetronate as A Versatile Electrophore for Pi-Extended Electron Acceptors

Yuki Hayashi, Yusuke Ishigaki, Jérémy Merad, Takanori Suzuki,* and Maurice Médebielle*

*Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan

Abstract

Bis[4-methoxy-5-methylenefuran-2(5H)-one]-type electron acceptors with anthracene-9,10-diyl and thiophene-2,5-diyl spacer were prepared by one-pot condensation of methyl tetronate with the corresponding dialdehydes. They undergo reversible electrochemical reduction, thus showing the potential utility of 5-arylidenetetronate as an electrophore for developing novel electron acceptors.

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