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Your search keyword '"Masayuki Yamashita"' showing total 18 results
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18 results on '"Masayuki Yamashita"'

6. The First Total Syntheses of (+)-Hostmanin A and (+)-Methyllinderatin

Author

Ai Kurume, Naoko Kitamura, Hiroki Iwasaki, Junko Kitao, Kenji Arimitsu, Nozomi Kumo, Masayuki Yamashita, and Minoru Ozeki

Subjects
Pharmacology, Chemistry, Methyllinderatin, Organic Chemistry, Absolute configuration, Physical chemistry, Total synthesis, Analytical Chemistry
Published
2011

7. Stereoselective Synthesis of 5-Substituted 2-Allyl-3-oxotetrahydrofuran-2-carboxylates Using Rhodium(II)-Catalyzed Oxonium Ylide Formation–[2,3] Shift

Author

Katsuaki Matsui, Masayuki Yamashita, Takayuki Yakura, and Kazumasa Matsuzaka

Subjects
Pharmacology, chemistry.chemical_classification, Organic Chemistry, chemistry.chemical_element, Medicinal chemistry, Analytical Chemistry, Catalysis, Rhodium, chemistry.chemical_compound, chemistry, Ylide, Stereoselectivity, Oxonium ion, Dichloromethane
Abstract

Reaction of 5-allyloxy-2-diazo-3-ketoesters 1 with catalytic amount of dirhodium(II) tetraacetate in dichloromethane proceeded in high yields with excellent stereoselectivities to give methyl 5-substituted 2-allyl-3-oxotetrahydrofuran-2-carboxylates 2, which are suitable intermediates for synthesis of heliespirones and their derivatives.

Published
2009

8. Improved Synthesis of (±)-Linderol A and Its First Conversion to (±)- 6-epi-Adunctin E

Author

Shunsaku Ohta, Tomoki Inaba, Ikuo Kawasaki, Ai Takada, Ikuko Takao, Takashi Shimizu, and Masayuki Yamashita

Subjects
Pharmacology, chemistry.chemical_compound, chemistry, Stereochemistry, Organic Chemistry, Adunctin E, Organic chemistry, Total synthesis, General Medicine, Transformation (music), Analytical Chemistry, Cyclobutane
Abstract

The synthetic route to a dibenzofuranone (7), a key intermediate of the total synthesis of (+)-linderol A (2), was considerably improved by using a novel stereoconvergent transformation of a cyclobutane (5), and the firstsynthesis of (′)-6-epi-adunctin E (8) was achieved by application of this route.

Published
2005

9. Bischler-Napieralski Reaction of N-[2-(2-Bromo-4,5-dialkyloxyphenyl)- ethyl]-N-(1-phenylethyl)-2-(2-bromo-4,5-dimethoxyphenyl)acetamides

Author

Ikuo Kawasaki, Masayuki Yamashita, Keiko Ohkita, Shunsaku Ohta, Naomi Hashimoto, Jun-ichi Kunitomo, Yoshitaka Ohishi, and Kumiko Miyatani

Subjects
Pharmacology, Stereochemistry, Chemistry, Organic Chemistry, Bischler–Napieralski reaction, Medicinal chemistry, Analytical Chemistry
Abstract

Direction of Bischler-Napieralski reaction of N-[2-(2-bromo- or 2-unsubstituted 4,5-dialkoxyphenyl)ethyl]-N-( 1-phenylethyl)-2-(2-bromo-4,5-dimethoxyphenyl)acetamides is discussed.

Published
2002

17. Photochemical Fries Rearrangement of N-Phenyl-2-pyrrolidone

Author

Shunsaku Ohta, Masayuki Yamashita, Masao Okamoto, and Atsunori Sano

Subjects
Pharmacology, chemistry.chemical_compound, Light source, chemistry, Fries rearrangement, Yield (chemistry), Organic Chemistry, Methanol, 2-Pyrrolidone, Piperylene, Photochemistry, Analytical Chemistry
Abstract

Photochemical Fries rearrangement of 1-phenyl-2-pyrrolidone (1) proceeded smoothly in methanol especially in the presence of piperylene. Continuous photo-irradiation of 1 successfully was carried out to raise the yield by utilizing a reaction mixture-circulation system consisting of a spiral quartz cell, a pump, a uv light source and a column packed with appropriate absorbents for the Fries rearranged product (3) and pigments

Published
1993

18. Synthesis and Application of Imidazole Derivatives. Synthesis of Pyrido[1,2-a]benzimidazolone Derivatives

Author

Ikuo Kawasaki, Teruyuki Yuasa, Eiji Minamii, Shunsaku Ohta, Masayuki Yamashita, and Yoshihiro Narita

Subjects
Pharmacology, Acylation, chemistry.chemical_compound, Benzimidazole, chemistry, Intramolecular reaction, Intramolecular force, Organic Chemistry, Imidazole, Aldol condensation, Medicinal chemistry, Analytical Chemistry
Abstract

Pyrido[1,2-a] benzimidazole derivatives (12a and 19a) were synthesized in moderate yields via an intramolecular aldol-condensation of 2-acetyl-1-formylmethylbenzimidazole (11) and an intramolecular acylation of the acylimidzolide (18) prepared from 2-ethoxycarbonylmethyl-1-(2-carboxyethyl)-benzimidazole (17), respectively

Published
1991

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