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320 results on '"Taga, Tooru"'

1. Hemilabile amidomonophosphine ligand-rhodium(I) complex-catalyzed asymmetric 1,4-addition of arylboronic acids to cycloalkenones

Author

Kuriyama, Masami, Nagai, Kazushige, Yamada, Ken-ichi, Miwa, Yoshinao, Taga, Tooru, and Tomioka, Kiyoshi

Subjects
Rhodium -- Research, Rhodium -- Chemical properties, Chemistry
Abstract

The report stated that asymmetric 1,4-addition reaction of arylboronic acids with cycloalkenones was catalyzed by 1 mol % of an amodomonophosphine-rhodium(1) catalyst in a 10:1 mixture of 1,4-dioxane and water at 100 degree C affording 3-arylcycloalkanones in reasonably high enantio selectively and high yields.

Published
2002

2. Catalytic role of metal ion in the selection of competing reaction paths: a first principles molecular dynamics study of the enzymatic reaction in ribozyme

Author

Boero, Mauro, Kiyoyuki Terakura, Tateno, Masaru, Miwa, Yoshinao, Taga, Tooru, and Tomioka, Kiyoshi

Subjects
Molecular dynamics -- Usage, Catalytic RNA -- Research, Catalytic RNA -- Structure, Catalytic RNA -- Atomic properties, Chemistry
Abstract

The study was conducted to investigate the mechanism of the enzymatic reaction of ribozyme by using finite temperature first principles molecular dynamics for both the anionic and the radical charge states of the modeled RNA fragment. The results indicate that the interplay between dynamical motion of the ions and electronic structure modifications occurring during the reaction were crucial in understanding the reaction mechanism.

Published
2002

3. Structural characterization, optical properties, and improved solubility of carbon nanotubes functionalized with WilkinsonEs catalyst

Author

Banerjee, Sarbajit, Wong, Stanislaus S., Yamada, Ken-ichi, Miwa, Yoshinao, Taga, Tooru, and Tomioka, Kiyoshi

Subjects
Nanotubes -- Usage, Carbon -- Research, Rhodium -- Research, Rhodium -- Atomic properties, Rhodium -- Structure, Chemistry
Abstract

The study states that oxidized carbon nanotubes reacte well with Wilkinson's complex. It is found that the Rh metal, coordinates to these nanotubes through the increased number of oxygen atoms forming a hexacoordinate structure around the Rh atom.

Published
2002

4. Stereospecific 1,3-migration of an Fe(CO) (sub)3 group on acyclic conjugated polyenes: application to remote and iterative asymmetric induction

Author

Takemoto, Yoshiji, Ishii, Kiyonori, Ibuka, Toshiro, Miwa, Yoshihisa, Taga, Tooru, Nakao, Syusuke, Tanaka, Tetsuaki, Ohishi, Hirofumi, Kai, Yasusi, and Kanehisa, Nobuko

Subjects
Chemistry, Organic -- Research, Iron -- Physiological aspects, Oxygen -- Physiological aspects, Carbon -- Physiological aspects, Polyenes -- Physiological aspects, Biological sciences, Chemistry
Abstract

Research has been conducted on the (acyclic-polyene)-Fe(CO) (sub)3 complexes. The stereochemical outcome of the Fe(CO) (sub)3 group migration on these complexes and their application to the remote and contiguous stereogenic centers are discussed.

Published
2001

5. Palladium(0)-catalyzed isomerization reactions of aziridines bearing an alpha, beta-unsaturated ester group: a thermodynamic preference for chiral alkyl (2E)--4,5-cis-4,5-epimino-N-(alkyl- or arylsulfonyl) 2-enoates over the other three stereoisomers

Author

Ibuka, Toshiro, Mimura, Norio, Ohno, Hiroaki, Nakai, Kazuo, Akaji, Masako, Habashita, Hiromu, Tamamura, Hirokazu, Miwa, Yoshihisa, Taga, Tooru, and Fujii, Nobutaka

Subjects
Organic compounds -- Synthesis, Palladium catalysts -- Usage, Isomerization -- Research, Biological sciences, Chemistry
Abstract

A practical procedure for the synthesis of (E)-alkene dipeptide isosteres was developed based on palladium(0)-catalyzed isomerization reactions. The synthetic process was characterized by the transformation of undesired 2-enoates into the target compounds via Pd(0)-catalyzed equilibrium reactions involving various 4,5-epimino-2-enoates. The strategic approach provides ready access to desired alpha,beta-enoates and subsequent transformation of the compounds into the desired dipeptide isosteres via a stereoselective manner.

Published
1997

6. A thermodynamic preference of chiral N-methanesulfonyl and N-arenesulfonyl 2,3-cis-3-alkyl-2-vinylaziridines over their 2,3-trans-isomers: useful palladium(0)-catalayzed equilibration reactions for the synthesis of (E)-alkene dipeptide isosteres

Author

Ibuka, Toshiro, Mimura, Norio, Aoyama, Hiroshi, Akaji, Masako, Ohno, Hiroaki, Miwa, Yoshihisa, Taga, Tooru, Nakai, Kazuo, Tamamura, Hirokazu, and Fujii, Nobutaka

Subjects
Peptides -- Synthesis, Stereoisomers -- Research, Biological sciences, Chemistry
Abstract

The equilibrated reactions of chiral N-(methanesulfonyl)- and N-(arenesulfonyl)-3-alkyl-2-vinylaziridines and N-(arenesulfonyl)-4-alkyl-5-vinyloxazolidine-2-ones, catalyzed by palladium(0), have been investigated. The results showed that the 2,3-cis-isomers are more stable that the corresponding 2,3-trans-isomers. A stereoselective method for the synthesis of (E)-alkene dipeptide isosteres is also presented.

Published
1997

8. 1,1'-binaphthalene-2,2'-diol as a chiral auxiliary. Diastereoselective alkylation of binaphthyl esters, complex-induced proximity effects in enolate formation, and one-step synthesis of an optically active beta-substituted ketone

Author

Tanaka, Fujie, Node, Manabu, Tanaka, Kiyoshi, Mizuchi, Maki, Hosoi, Shinzo, Nakayama, Masayo, Taga, Tooru, and Fuji, Kaoru

Subjects
Organic compounds -- Synthesis, Alkylation -- Observations, Stereochemistry -- Research, Chemistry
Abstract

The diastereoselective alkylation of a binaphthyl ester obtained from (S)-naphthyl phenylacetate, using LDA as a base in THF produces an S,S-isomer as the major product. The increase in the diastereomeric excess by using n-BuLi, is due to the complex-induced proximity effect during enolate formation. During enolate formation, the (E)-enolate is the major product from phenyl phenylacetate. The treatment of organometallics to binaphthyl ester results in the formation of respective optically active ketones.

Published
1995

9. Aza-Payne rearrangement of activated 2-aziridinemethanols and 2,3-epoxy amines under basic conditions

Author

Ibuka, Toshiro, Nakai, Kazuo, Habashita, Hiromu, Hotta, Yuka, Otaka, Akira, Tamamura, Hirokazu, Fujii, Nobutaka, Mimura, Norio, Miwa, Yoshihisa, Taga, Tooru, Chounan, Yukiyasu, and Yamamoto, Yoshinori

Subjects
Epoxy compounds -- Research, Alcohols -- Research, Rearrangements (Chemistry) -- Research, Biological sciences, Chemistry
Abstract

Epoxysulfonamides are formed by aza-Payne rearrangement of activated 2-aziridinemethanols with t-BuOK, NaH, or KH at 0 degrees celsius in THF, toluene, or 1,4-dioxane followed by quenching at -78 degrees celsius. Treatment of N-tosyl(2S)-azetidinemethanol and N-tosyl (S)-prolinol with NaH or KH in dichloromethane yields only dimeric compounds. Nucleophilic ring opening of the aziridine predominates if the nucleophile is highly reactive.

Published
1995

10. Diastereoselective Diels-Alder cycloadditions with chiral 1-(alkylsulfinyl)-2-nitroalkenes

Author

Fuji, Kaoru, Tanaka, Kiyoshi, Abe, Hitoshi, Matsumoto, Kiyoshi, Harayama, Takashi, Ikeda, Atsutoshi, Taga, Tooru, Miwa, Yoshihisa, and Node, Manabu

Subjects
Nitrobenzenes -- Research, Diels-Alder reaction -- Analysis, Stereochemistry -- Analysis, Biological sciences, Chemistry
Abstract

The chiral 1-(alkylsulfinyl)-2-nitroalkenes, whose preparation involved diastereoselective cycloadditions of trisubstituted dienophiles with cyclopentadiene in the presence of Lewis acids, was developed as dienophiles for assymetric Diels-Alder reactions. E-dienophiles revealed a lower diastereo- and endo/exo-selectivity than did the Z-sulfinyldienophiles.

Published
1994

13. Syn-S(sub N)2' pathway in the reaction of certain gamma-(mesyloxy) alpha, beta-enoates with RCu(CN)MgX-BF3 reagents: importance of MgX and bulky R group upon the diastereoselectivity

Author

Ibuka, Toshiro, Taga, Tooru, Habashita, Hiromu, Nakai, Kazuo, Tamamura, Hirokazu, Fujii, Nobutaka, Chounan, Yukiyasu, Nemoto, Hisao, and Yamamoto, Yoshinori

Subjects
Olefins -- Research, Organosulfur compounds -- Research, Serine -- Research, Threonine -- Research, Substitution reactions -- Research, Organometallic compounds -- Research, Copper compounds -- Research, Biological sciences, Chemistry
Abstract

alpha,beta-Unsaturated gamma-mesylates from (S)-serine and (S)-threonine undergo bimolecular substitution reactions with alkylcyanocuprate-boron trifluoride reagents. The stereochemical study shows that while anti- mesylates yield the expected anti-substitution products, the reaction course of the syn-mesylates depends on the reagent used. Primary alkyl reagents form diastereomeric mixtures while isopropyl and tert-butyl reagents yield syn- products with high diastereoselectivity.

Published
1993

14. Diastereoselective alkylative discrimination of racemic 3-substituted 4-acetoxyazetidin-2-ones and its application to the synthesis of a chiral key intermediate for carbapenem syntheses

Author

Nagao, Yoshimitsu, Nagase, Yunosuke, Kumagai, Toshio, Kuramoto, Yasuhiro, Kobayashi, Shigeaki, Inoue, Yoshinori, Taga, Tooru, and Ikeda, Hirokazu

Subjects
Organic compounds -- Synthesis, Antineoplastic agents -- Research, Azo compounds -- Research, Alkylation -- Methods, Enantiomers -- Research, Carbamates -- Usage, Organometallic compounds -- Usage, Biological sciences, Chemistry
Abstract

The chiral tin enolate of 3-acetyl-(4S)-ethyl-1, 3-thiazolidine-2-thione effects a highly diastereoselective alkylation of 3-dimethylsilyloxy-4-acetoxyazetidin-2-one and its stereoisomer, giving 42:20:9 and 45:29:5 respective enantiomeric yields. The major enantiomer and its carboxylic acid derivative are transformed into a carboxylate, which can serve as a key intermediate in the synthesis of carbapenems. To evaluate the enantiomeric purity of chiral 4-acetoxyazetidin-2-one for research and industrial use, it is subjected to analytical resolution on an amylose (S)-methylbenzylcarbamate column. Other stereochemical data are presented.

Published
1992

19. Molecular assembly and gelating behavior of didodecanoylamides of alpha, omega-alkylidenediamines

Author

Tomioka, Kiyoshi, Sumiyoshi, Takaaki, Handa, Tetsuro, Narui, Shinobu, Nakano, Minoru, Nagaoka, Yasuo, Taga, Tooru, Iida, Akira, and Miwa, Yoshihisa

Subjects
Amides -- Research, Chemistry
Abstract

The study describes that didodecanoylamides of alpha, omega-alkylidenediamines assemble into structures due to van der Waals interactions. Description of systematic studies of the arrangement of two amide groups for a self-complementary assembly is given.

Published
2001

20. First palladium-catalyzed aziridination reaction of amino allenes

Author

Ohno, Hiroaki, Toda, Ayako, Miwa, Yoshihisa, Taga, Tooru, Osawa, Eriko, Yamaoka, Yumiko, Fujii, Nobutaka, and Ibuka, Toshiro

Subjects
Organic compounds -- Synthesis, Amino compounds -- Research, Ring formation (Chemistry) -- Research, Biological sciences, Chemistry
Abstract

A simple method for the conversion of amino allenes into sterically congested aziridines is reported for the first time. These aziridines are not readily accessible by other means. The chiral amino allenes were used in the synthes of the congested 2-alkenylaziridines, with the solvent employed proving to be the most dominant factor in determining the site of intramolecular cyclization leading to aziridines. Dioxane was found to be the best solvent for the aziridination of amino allenes and arylation took place at the allenic central carbon to afford 2-alkenylaziridines in good yields.

Published
1999

31. Regio- and stereoselective ring-opening of chiral 1,3-oxazolidin-2-one derivatives by organocopper reagents provides novel access to di-, tri- and tetra-substituted alkene dipeptide isosteresElectronic supplementary information (ESI) available: synthetic procedures and characterization for 4a,b, 5a,b, 7b, 8a,b, 9a,b, 10b, 11a,b, 12b,c, 13b, 14a,b, 15, 16a,b, 17a,b, 18, 19b, 20b. See http://www.rsc.org/suppdata/p1/b2/b203482d/

Author

Oishi, Shinya, primary, Niida, Ayumu, additional, Kamano, Takae, additional, Miwa, Yoshihisa, additional, Taga, Tooru, additional, Odagaki, Yoshihiko, additional, Hamanaka, Nobuyuki, additional, Yamamoto, Mikio, additional, Ajito, Keiichi, additional, Tamamura, Hirokazu, additional, Otaka, Akira, additional, and Fujii, Nobutaka, additional

Published
2002
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36. Erratum to “Effect of DNA/liposome mixing ratio on the physicochemical characteristics, cellular uptake and intracellular trafficking of plasmid DNA/cationic liposome complexes and subsequent gene expression”

Author

Sakurai, Fuminori, primary, Inoue, Rui, additional, Nishino, Yasunobu, additional, Okuda, Ayumu, additional, Matsumoto, Osamu, additional, Taga, Tooru, additional, Yamashita, Fumiyoshi, additional, Takakura, Yoshinobu, additional, and Hashida, Mitsuru, additional

Published
2000
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44. Palladium(0)-Catalyzed Isomerization Reactions of Aziridines Bearing an α,β-Unsaturated Ester Group: A Thermodynamic Preference for Chiral Alkyl (2E)-4,5-cis-4,5-Epimino-N-(alkyl- or arylsulfonyl) 2-Enoates over the Other Three Stereoisomers

Author

Ibuka, Toshiro, primary, Mimura, Norio, additional, Ohno, Hiroaki, additional, Nakai, Kazuo, additional, Akaji, Masako, additional, Habashita, Hiromu, additional, Tamamura, Hirokazu, additional, Miwa, Yoshihisa, additional, Taga, Tooru, additional, Fujii, Nobutaka, additional, and Yamamoto, Yoshinori, additional

Published
1997
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