研究者詳細 - 坂倉　彰

論文 - 坂倉　彰

分割表示 103 件中 21 - 40 件目／全件表示 >>

Regioselective DMAD-insertion reaction of silyl dienol ether of γ-pyrone under catalyst- and heating-free conditions 査読

Ichiro Hayakawa, Yuji Yamanaka, Koichi Mitsudo, Hiromi Ota, Akira Sakakura

Heterocycles 94 ( 12 ) 2299 - 2306 2017年12月

Diastereodivergent Henry Reaction for the Stereoselective Construction of Nitrogen-Containing Tetrasubstituted Carbons: Application to Total Synthesis of Manzacidins A and C 査読

Takayuki Kudoh, Yuya Araki, Natsumi Miyoshi, Mizuho Tanioka, Akira Sakakura

ASIAN JOURNAL OF ORGANIC CHEMISTRY 6 ( 12 ) 1760 - 1763 2017年12月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

beta,beta,-Disubstituted -amino alcohols has been synthesized in a diastereodivergent manner from chiral secondary nitroalkanes as starting materials. In this key Henry reaction, the use of different protecting groups resulted in the diastereoselective construction of the tetrasubstituted carbon stereocenter with different configuration. Based on this methodology, a total synthesis of manzacidins A and C has been achieved.

DOI： 10.1002/ajoc.201700568

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Heat Versus Basic Conditions: Intramolecular Dehydro-Diels–Alder Reaction of 1-Indolyl-1,6-heptadiynes for the Selective Synthesis of Substituted Carbazoles 査読

Takayuki Kudoh, Syo Fujisawa, Megumi Kitamura, Akira Sakakura

Synlett 28 ( 16 ) 2189 - 2193 2017年10月

Reinvestigation of the Biomimetic Cyclization of 3,5-Diketoesters: Application to the Total Synthesis of Cyercene A, an α-Methoxy-γ-Pyrone-Containing Polypropionate 査読

Kai Onda, Ichiro Hayakawa, Akira Sakakura

Synlett 28 ( 13 ) 1596 - 1600 2017年8月

Discovery of O6-benzyl glaziovianin A, a potent cytotoxic substance and a potent inhibitor of α,β-tubulin polymerization 査読

Ichiro Hayakawa, Shuya Shioda, Takumi Chinen, Taisei Hatanaka, Haruna Ebisu, Akira Sakakura, Takeo Usui, Hideo Kigoshi

Bioorganic and Medicinal Chemistry 24 ( 21 ) 5639 - 5645 2016年11月

A short access to 3,5-disubstituted piperazinones based on the aza-Michael addition of α-amino esters to β-substituted nitroalkenes 査読

Takayuki Kudoh, Seiji Isoyama, Sachiko Kagimoto, Katsutoshi Kurihara, Akira Sakakura

Tetrahedron Letters 57 ( 42 ) 4693 - 4696 2016年10月

Enantioselective bromocyclization of 2-geranylphenols induced by chiral phosphite-urea bifunctional catalysts 査読

Yasuhiro Sawamura, Yoshihiro Ogura, Hidefumi Nakatsuji, Akira Sakakura, Kazuaki Ishihara

CHEMICAL COMMUNICATIONS 52 ( 36 ) 6068 - 6071 2016年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Chiral phosphite-urea bifunctional catalysts have been developed for the enantioselective bromocyclization of 2-geranylphenols with N-bromophthalimide (NBP) for the first time. The chiral triaryl phosphite moiety activates NBP to generate a bromophosphonium ion. On the other hand, the urea moiety interacts with a hydroxyl group of the substrate through hydrogen bonding interactions. Enantioselectivity is effectively induced through two-point attractive interactions between the catalyst and the substrate.

DOI： 10.1039/c6cc00229c

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Stereoselective Electrophilic Cyclization 査読

Akira Sakakura, Kazuaki Ishihara

CHEMICAL RECORD 15 ( 4 ) 728 - 742 2015年8月

担当区分：筆頭著者,　責任著者記述言語：英語出版者・発行元：WILEY-V C H VERLAG GMBH

Electrophilic cyclizations of unactivated alkenes play highly important roles in the synthesis of useful building blocks. This account describes our contributions to the rational design of monofunctionalized chiral Lewis base catalysts for enantioselective iodo- and protocyclizations. For the stereoselective promotion of electrophilic bromocyclizations, nucleophilic phosphite-urea cooperative catalysts have been designed.

DOI： 10.1002/tcr.201500005

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Enantioselective 1,3-Dipolar Cycloaddition of Azomethine Imines with Propioloylpyrazoles Induced by Chiral π-Cation Catalysts 査読

Masahiro Hori, Akira Sakakura, Kazuaki Ishihara

Journal of the American Chemical Society 136 ( 38 ) 13198 - 13201 2014年9月

Selective Bromocyclization of 2-Geranylphenols Promoted by Phosphite-Urea Cooperative Catalysts 査読

Yasuhiro Sawamura, Hidefumi Nakatsuji, Matsujiro Akakura, Akira Sakakura, Kazuaki Ishihara

CHIRALITY 26 ( 7 ) 356 - 360 2014年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

Nucleophilic phosphite-urea cooperative catalysts are highly efficient for the bromonium-induced cyclization of 2-geranylphenols. Phosphite-N,N'-dimethylurea catalysts also show moderate activity, probably due to the steric effect of their bent conformation. Chirality 26:355-359, 2014. (c) 2014 Wiley Periodicals, Inc.

DOI： 10.1002/chir.22297

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Cooperative Activation with Chiral Nucleophilic Catalysts and N-Haloimides: Enantioselective Iodolactonization of 4-Arylmethyl-4-pentenoic Acids 査読

Hidefumi Nakatsuji, Yasuhiro Sawamura, Akira Sakakura, Kazuaki Ishihara

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 53 ( 27 ) 6974 - 6977 2014年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

Chiral triaryl phosphates promote the enantioselective iodolactonization of 4-substituted 4-pentenoic acids to give the corresponding iodolactones in high yields with high enantioselectivity. N-Chlorophthalimide (NCP) is employed as a Lewis acidic activator and oxidant of I-2 for the present iodolactonization. In combination with 1.5 equivalents of NCP, only 0.5 equivalents of I-2 are sufficient to generate the iodinating reagent.

DOI： 10.1002/anie.201400946

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Catalytic Enantioselective Inverse Electron Demand Hetero-Diels-Alder Reaction with Allylsilanes 査読

Yuki Matsumura, Takahiro Suzuki, Akira Sakakura, Kazuaki Ishihara

ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 53 ( 24 ) 6131 - 6134 2014年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-V C H VERLAG GMBH

The first diastereo- and enantioselective inverse electron demand hetero-Diels-Alder reaction of beta,gamma-unsaturated alpha-ketoesters with allylsilanes is described. Chiral copper( II) catalysts successfully activate the beta,gamma-unsaturated alpha-ketoesters and promote the reaction with allylsilanes with excellent enantioselectivities. This process represents a new entry to chiral oxanes.

DOI： 10.1002/anie.201402934

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Enantioselective Cyanoethoxycarbonylation of Isatins Promoted by a Lewis Base–Brønsted Acid Cooperative Catalyst 査読

Yoshihiro Ogura, Matsujiro Akakura, Akira Sakakura, Kazuaki Ishihara

Angewandte Chemie International Edition 52 ( 32 ) 8299 - 8303 2013年8月

Primary Alkylboronic Acids as Highly Active Catalysts for the Dehydrative Amide Condensation of α-Hydroxycarboxylic Acids 査読

Risa Yamashita, Akira Sakakura, Kazuaki Ishihara

Organic Letters 15 ( 14 ) 3654 - 3657 2013年7月

Kinetic Resolution of Racemic Carboxylic Acids through Asymmetric Protolactonization Promoted by Chiral Phosphonous Acid Diester 査読

Masayuki Sakuma, Akira Sakakura, Kazuaki Ishihara

ORGANIC LETTERS 15 ( 11 ) 2838 - 2841 2013年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Chiral phosphonium salts induce the kinetic resolution of racemic a-substituted unsaturated carboxylic acids through asymmetric protolactonization. Both the lactones and the recovered carboxylic acids are obtained with high enantioselectivities and high S (=k(fast)/k(slow)) values. Asymmetric protolactonization also leads to the desymmetrization of achiral carboxylic acids. Notably, chiral phosphonous acid diester not only induced the enantioselectivity but also promoted protolactonization.

DOI： 10.1021/ol401313d

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“Phosphite–Urea” Cooperative High-Turnover Catalysts for the Highly Selective Bromocyclization of Homogeranylarenes 査読

Yasuhiro Sawamura, Hidefumi Nakatsuji, Akira Sakakura, Kazuaki Ishihara

Chemical Science 4 ( 11 ) 4181 - 4186 2013年

α-Heterosubstituted β-Alkylacroleins as Useful Multisubstituted Dienophiles for Enantioselective Diels-Alder Reactions 査読

Akira Sakakura, Hiroki Yamada, Kazuaki Ishihara

Asian Journal of Organic Chemistry 1 ( 2 ) 133 - 137 2012年10月

Enantioselective Diels–Alder Reaction of α-(Acylthio)acroleins: a New Entry to Sulfur-containing Chiral Quaternary Carbons 査読

Akira Sakakura, Hiroki Yamada, Kazuaki Ishihara

Organic Letters 14 ( 12 ) 2972 - 2975 2012年6月

N,N-Diarylammonium Pyrosulfate as a Highly Effective Reverse Micelle-Type Catalyst for Hydrolysis of Esters 査読

Yoshiki Koshikari, Akira Sakakura, Kazuaki Ishihara

ORGANIC LETTERS 14 ( 12 ) 3194 - 3197 2012年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Reverse micelle-type N,N-diarylammonium pyrosulfate (3-5 mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for alpha-heterosubstituted carboxylic acids.

DOI： 10.1021/ol301290c

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Hydrophobic N,N-Diarylammonium Pyrosulfates as Dehydrative Condensation Catalysts under Aqueous Conditions 査読

Akira Sakakura, Yoshiki Koshikari, Matsujiro Akakura, Kazuaki Ishihara

ORGANIC LETTERS 14 ( 1 ) 30 - 33 2012年1月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Oil-soluble N,N-diarylammonium pyrosulfates as nonsurfactant-type catalysts for the dehydrative ester condensation under aqueous conditions are described. Preheat treatment of dibasic sulfuric acid with bulky N,N-diarylamines generates water-tolerant salts of pyrosulfuric acid as active catalyst species. The present catalysts in water can also widely be applied to unusual selective esterifications and dehydrative glycosylation.

DOI： 10.1021/ol2027366

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