Special Issue

Masakatsu Shibasaki's Special Issues, Vol. 95, No. 2, 2017

48 data found. 31 - 48 listedFirst Previous
Paper | Special issue | Vol 95, No. 2, 2017, pp. 1074 - 1081
Published online: 29th December, 2016
DOI: 10.3987/COM-16-S(S)79
Synthetic Studies of Liposidomycin Degradation Product: Model Studies of Diazepanone Ring Construction

Noriyuki Nakajima,* Taichi Seida, Ai Furuno, Takayuki Asahi, Takao Kishimoto, and Masahiro Hamada

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

Abstract

The model studies of diazepanone ring construction of liposidomycin degradation product was described. A synthesis of the liposidomycin diazepanone ring system using 2-nitrobenzenesulfonamides (N-Ns) as an activating and a protecting group has been achieved. Under the intramolecular Mitsunobu reaction conditions, the cyclization reaction proceeded efficiently to give seven-membered ring systems.

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Paper | Special issue | Vol 95, No. 2, 2017, pp. 1082 - 1105
Published online: 21st February, 2017
DOI: 10.3987/COM-16-S(S)81
An Asymmetric Total Synthesis of Martinellic Acid

Vivek Badarinarayana, Hossen Mahmud, and Carl J. Lovely*

*Department of Chemistry and Biochemistry, University of Texas Arlington, Arlington, TX76019, U.S.A.

Abstract

We describe an asymmetric total synthesis of the pyrrolo[3,2-c]quinoline natural product martinellic acid starting from pyrroglutamic acid. A convergent strategy involving a Pd-catalyzed aryl amination reaction of a chiral, non-racemic pyrrolidine derivative incorporates the C2-chiral center which controls the remaining two stereocenters. Elaboration of this adduct through a Grieco-elimination sets the stage for a diastereoselective intramolecular [3+2] azomethine ylide-alkene cycloaddition and the construction of the remaining two chiral centers. Elaboration of the cycloadduct and incorporation the prenyl guanidine units delivered martinellic acid after removal of the protecting groups.

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Paper | Special issue | Vol 95, No. 2, 2017, pp. 1106 - 1120
Published online: 16th February, 2017
DOI: 10.3987/COM-16-S(S)82
Toward the Synthesis of (‒)-Codeine by Chiral Auxiliary-Mediated Nitrone Cycloaddition

Julia Rautschek and Peter Metz*

*Department of Chemistry, Organic Chemistry I, Technische Universität Dresden, Bergstraße 66, 01069 Dresden, Germany

Abstract

Application of a C2-symmetric dioxolane moiety as chiral auxiliary for an asymmetric intramolecular nitrone cycloaddition was studied as a possible key step for the enantioselective synthesis of (–)-codeine. A cycloaddition precursor bearing a 1,2-diphenylethylene acetal was selected that was readily accessible in ten steps from isovanillin. It underwent nitrone cycloaddition and after a consecutive transformation, an isoxazolidine intermediate with the absolute and relative configuration required for (–)-codeine was obtained.

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Paper | Special issue | Vol 95, No. 2, 2017, pp. 1121 - 1131
Published online: 14th February, 2017
DOI: 10.3987/COM-16-S(S)83
Catalytic Intramolecular [2+2+2] Cycloaddition of Peptide-Tethered Branched Triynes for the Synthesis of Cyclic Peptides

Shuhei Obinata, Yu-ki Tahara, Kyalo Stephen Kanyiva, and Takanori Shibata*

*Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan

Abstract

Rhodium-catalyzed intramolecular [2+2+2] cycloaddition of peptide-tethered branched triynes gave cyclic peptides in moderate to excellent yields. This is a new catalytic protocol for the synthesis of cyclic peptides containing various amino acids.

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Paper | Special issue | Vol 95, No. 2, 2017, pp. 1132 - 1147
Published online: 31st January, 2017
DOI: 10.3987/COM-16-S(S)84
Ammonium Hypoiodite-Catalyzed Peroxidative Dearomatization of Phenols

Muhammet Uyanik, Kohei Nishioka, and Kazuaki Ishihara*

*Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8603, Japan

Abstract

Here, we report the first transition metal-free peroxidative dearomatization of phenols using hypoiodite catalysis with TBHP. Hypoiodite salts are generated in situ from the corresponding quaternary ammonium iodides in the presence of TBHP, and the oxidative coupling reaction proceeds efficiently under mild conditions. The dearomatized products are versatile synthetic intermediates for further synthetic transformations to various complex structures including heterocycles. As a demonstration, the further oxidation of the unsaturated peroxide with TBHP afforded the corresponding peroxy epoxide in good yield.

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Paper | Special issue | Vol 95, No. 2, 2017, pp. 1148 - 1158
Published online: 17th February, 2017
DOI: 10.3987/COM-16-S(S)88
Synthesis and Crystal Structures of Dicobalt Hexacarbonyl Complexes of Dicationic Alkyne-Bridged Imidazolium and Triazolium Derivates

Simone Haslinger, Gerhard Laus, Stefan Oberparleiter, Klaus Wurst, Volker Kahlenberg, Sven Nerdinger,* Erwin Schreiner, and Herwig Schottenberger

*Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

Dicationic alkyne-bridged imidazolium and triazolium chlorides were subjected to counter-ion replacement reaction with weakly coordinating anions, such as hexafluoridophosphate and bis(trifluoromethanesulfonyl)amide. The resulting low-melting salts were further functionalized to dicobalt hexacarbonyl adducts. Seven crystal structures were determined by X-ray diffraction. Interionic C–H...F and C–H...O contacts were observed.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1159 - 1166
Published online: 1st February, 2017
DOI: 10.3987/COM-16-S(S)55
Preparation and Optical and Electrochemical Properties of Diphthalocyanine Linked with a TTF Unit

Takeshi Kimura,* Shomu Sasaki, and Shiduko Nakajo

*Center for Instrumental Analysis, Iwate University, Morioka, Iwate 020-8551, Japan

Abstract

4,4’,7,7’-Tetrabutyl-5,5’,6,6’-tetracyano-2,2’-bis(benzo-1,3-dithiol-2-ylidene) (3-Bu) was prepared and mixed with 4,5-bis(2,6-dimethylphenoxy)phthalonitrile (4), which was treated with lithium alkoxide at 120 °C to produce diphthalocyanine linked with a TTF unit. The structure of the product was determined by NMR and MALDI-TOF-MS. The optical and electrochemical properties were examined by UV-vis spectra and cyclic voltammetry.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1167 - 1176
Published online: 31st January, 2017
DOI: 10.3987/COM-16-S(S)65
Syntheses and Photophysical Properties of Aminobenzopyranoxanthene Dyes Containing Various Alkyl Chains at Amine Moieties

Shinichiro Kamino,* Masaru Tanioka, Daisuke Sawada, and Shuichi Enomoto*

*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan

Abstract

Aminobenzopyranoxanthene (ABPX) dyes containing linear n-alkyl chains at amino groups were synthesized, and their cis and trans stereoisomers were isolated. Detailed spectrophotometric studies revealed that all the ABPX derivatives exhibited fluorescence emission in the far-red and near-infrared wavelength regions, and their fluorescence quantum efficiency increased with increasing n-alkyl chain length. Almost no differences in photophysical properties were observed between the cis and trans stereoisomers.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1177 - 1183
Published online: 24th January, 2017
DOI: 10.3987/COM-16-S(S)66
Synthesis of 2-Aroyl-1-methyl-1H-imidazoles Using Aryl Carboxylic Acids

Kin-ichi Oyama,* Noriyuki Watanabe, and Kumi Yoshida*

*Graduate School of Information Science, Nagoya University, Chikusa, Nagoya, 464-8601, Japan

Abstract

A new and useful reaction for the synthesis of 2-aroyl-1-methyl-1H-imidazoles using free aryl carboxylic acids was developed. This method was applicable to naphthoic acid and benzoic acid derivatives to give each target compound with up to 80% yield.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1184 - 1196
Published online: 16th February, 2017
DOI: 10.3987/COM-16-S(S)67
Halocyclizations and Cycloisomerizations of Bisaryl 1,6-Diynes

Kyle R. Strom, Anna C. Impastato, Jaime A. Duque, and John K. Snyder*

*Department of Chemistry, Boston University, Boston, Massachusetts 02215, U.S.A.

Abstract

N-Sulfonamide tethered bisaryl 1,6-diynes underwent cyclization in the presence of Ga(III) trihalide to give mixtures of halocyclization (HC) and Friedel-Crafts (FC) cycloisomerization products. The ratio of products was found to be dependent on the identity of the halide and diyne substrate. In contrast, under Bronsted acid conditions only Friedel-Crafts cycloisomerization products were obtained. The regiochemical preference of the cyclization under Bronsted acid catalysis was reversed under Lewis acid catalysis. Herein, we report our efforts to understand and make use of this disparity to access a range of vinyl halides and indenopyridines from readily accessible 1,6-diyne.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1197 - 1203
Published online: 24th January, 2017
DOI: 10.3987/COM-16-S(S)69
Synthesis of Cyclic Nigerosylnigerose (CNN) bis-Imidazolium Salts

Susumu Tsuda,* Yuya Komatsu, Yohei Minami, Ryoji Ueda, Shin-ichi Fujiwara, Takanori Iwasaki, Hitoshi Kuniyasu, and Nobuaki Kambe*

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan

Abstract

Cyclic nigerosyl-(16)-nigerose (CNN) monotosylate 1 and CNN ditosylate 2 were prepared and characterized by MALDI-TOF mass and NMR Spectroscopies. CNN bis-imidazolium salts 3 were also obtained by nucleophilic displacement reaction of 2 with imidazoles.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1204 - 1210
Published online: 14th February, 2017
DOI: 10.3987/COM-16-S(S)71
A Short Synthetic Route to a Hybrid Molecule Benzosultine-Sulfone via [2+2+2] Cyclotrimerization Using Mo(CO)6

Sambasivarao Kotha* and Gaddamedi Sreevani

*Department of Chemistry, Indian Institute of Technology-Bombay, Powai, Mumbai-400076, India

Abstract

Here, we report an improved and short synthetic route to benzosultine-sulfone via [2+2+2] cyclotrimerization as a key step, starting with dipropargyl ether and 1,4-dibromo-2-butyne with an overall yield of 16%.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1211 - 1229
Published online: 6th February, 2017
DOI: 10.3987/COM-16-S(S)72
Diastereo- and Enantioselective Construction of 6,7-Dioxabicyclo[2.2.1]heptane Derivatives by a Dirhodium(II)-Catalyzed Intramolecular C–H Insertion Reaction

Taku Miyazawa, Kozue Imai, Motoki Ito, Koji Takeda, Masahiro Anada,* Shigeki Matsunaga, and Shunichi Hashimoto*

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

Abstract

The first diastereo- and enantioselective construction of bridged bicyclic ring systems by an intramolecular C–H insertion reaction is described. With dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh2(S-PTTL)4, the C–H insertion of α-alkyl-α-diazoesters containing an ethylene ketal moiety at the γ-position provided methyl 6,7-dioxabicyclo[2.2.1]heptane-3-carboxylate derivatives with up to 95% ee and perfect diastereoselectivity.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1230 - 1244
Published online: 18th November, 2016
DOI: 10.3987/COM-16-S(S)74
Synthesis of a Functionalized Morphan Scaffold via a Palladium-Catalyzed Cycloalkenylation and Beckmann Rearrangement

Natsuko Kagawa, Yutaka Yamamoto, Shuichiro Ono, and Masahiro Toyota*

*Department of Chemistry, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuencho, Sakai, Osaka 599-8531, Japan

Abstract

Functionalized 2-azabicyclo[3.3.1]nonan-3-ones, potential precursors to morphan, were assembled using a combination of a palladium-catalyzed cycloalkenylation and a Beckmann rearrangement.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1245 - 1253
Published online: 15th February, 2017
DOI: 10.3987/COM-16-S(S)80
A Fischer Indolization Strategy toward the Total Synthesis of (–)-Goniomitine

Beau P. Pritchett, Jun Kikuchi, Yoshitaka Numajiri, and Brian M. Stoltz*

*The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Blvd. MC101-20, Pasadena, CA 91125, U.S.A.

Abstract

A Fischer indolization strategy toward the core of (–)-goniomitine is reported. Initial investigations into the Pd-catalyzed asymmetric allylic alkylation of dihydropyrido[1,2-a]indolone (DHPI) substrates are also discussed.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1254 - 1260
Published online: 16th February, 2017
DOI: 10.3987/COM-16-S(S)85
Azulene-Based Tetrathiafulvalenes: Preparation and Their Electron-Donating Ability

Ohki Sato,* Takahito Saito, Masami Aoki, and Atsushi Sakai

*Department of Chemistry, Graduate School of Science and Engineering, Saitama University, Shimo-okubo 255, Sakura-ku, Saitama 338-8570, Japan

Abstract

The condensation reaction of dithiocarbonates derived from azuleno- and guaiazulenopentathiepin with vinylene trithiocarbonate and the ethylenedithio derivative in triethyl phosphite afforded azulene-based tetrathiafulvalenes [Az-TTF, Az-(EDT)TTF, GAz-TTF and GAz-(EDT)TTF], respectively. The vinylene derivatives (Az-TTF and GAz-TTF) showed slightly higher electron-donating ability than the corresponding ethylenedithio ones [Az-(EDT)TTF and GAz-(EDT)TTF] by CV measurement. GAz-TTFs produced charge transfer complexes with tetracyanoquinodimethane, respectively.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1261 - 1271
Published online: 21st February, 2017
DOI: 10.3987/COM-16-S(S)89
Asymmetric Biocatalytic Reduction of Cyclic Imines: Design and Application of a Tailor-Made Whole-Cell Catalyst

Nadine Zumbrägel, Dennis Wetzl, Hans Iding, and Harald Gröger*

*Chair of Organic Chemistry I, Faculty of Chemistry, Bielefeld University, Univesitätsstr. 25, 33615 Bielefeld, Germany

Abstract

The design of a recombinant whole-cell catalyst and its utilization in the asymmetric reduction of 1-methyl-3,4-dihydroisoquinoline chosen as a model substrate for cyclic imines is presented. As “designer cells” E. coli cells bearing the two enzymes imine reductase and glucose dehydrogenase (for in situ-cofactor recycling) were constructed, which turned out to be suitable for the asymmetric reduction of 1-methyl-3,4-dihydroisoquinoline at low biocatalyst loading of 2 g/L up to 10 g/L of lyophilized cells, leading to both high conversion and enantioselectivity of >99% ee of the resulting amine. The stoichiometric reducing agent is readily available d-glucose, and a proof of concept for running the reactions at elevated substrate concentration of up to100 mM was demonstrated.

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Short Paper | Special issue | Vol 95, No. 2, 2017, pp. 1272 - 1284
Published online: 17th February, 2017
DOI: 10.3987/COM-16-S(S)90
Selective Aryl Radical Transfers into N-Heteroaromatics from Diaryliodonoium Salts with Trimethoxybenzene Auxiliary

Toshifumi Dohi, Shohei Ueda, Akiko Hirai, Yusuke Kojima, Koji Morimoto, and Yasuyuki Kita*

*Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan

Abstract

We have found that a series of trimethoxybenzene-based diaryliodonium(III) salts I (ArI+Ar’X-, where Ar = various aryl groups, Ar’ = 2,4,6-trimethoxyphenyl, X- = counterion) can exclusively cause Ar-transfers during the base-induced radical couplings with N-heteroaromatic compounds 1 by working the trimethoxybenzene ring (Ar’) as an inert coupling auxiliary. By the treatment with N-heteroaromatics 1 as the solvent, the metal-free arylations utilizing the specific salts I initiated by solid NaOH upon heating selectively produced the corresponding biaryls 2 in good yields without the formation of the trimethoxybenzene (Ar’) coupling product.

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