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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-dihydropyrazolo[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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104 data found. 91 - 104 listedFirst Previous