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Your search keyword '"Bando, Masahiko"' showing total 77 results
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77 results on '"Bando, Masahiko"'

62. Tricalysiolide G and tricalysiols A and B: rearranged ent-kaurane-type and e nt-kaurane-type diterpenoids from the leaves of Tricalysia dubia (Lindl.) Ohwi.

Author

He, Dong-Hui, Matsunami, Katsuyoshi, Otsuka, Hideaki, Shinzato, Takakazu, Aramoto, Mitsunori, Bando, Masahiko, and Takeda, Yoshio

Abstract

Three rearranged ent-kaurane diterpenes with the cafestol-type framework have been isolated from the leaves of Tricalysia dubia. Two were found to be known diterpenoids, tricalysiolides B and C. Tricalysiolide B was isolated as colorless prisms in this experiment and its three-dimensional structure was determined by X-ray crystallography. The remaining diterpenoid was a new compound and was named tricalysiolide G. Two new ent-kaurane-type diterpenoids, given the trivial names tricalysiol A and tricalysiol B, were also isolated. The structures of the new compounds were elucidated from spectroscopic evidence. [ABSTRACT FROM AUTHOR]

Published
2007
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63. Synthesis and Structure of Orobanchol, the Germination Stimulant for Orobanche minor

Author

Matsui, Junichi, Yokota, Takao, Bando, Masahiko, and Takeuchi, Yasutomo

Abstract

The structure of orobanchol, a new seed germination stimulant for clover broomrape (Orobanche minor), was proposed as 5a (tentative absolute configuration) on the basis of GC-MS comparison of the natural product with several synthetic compounds [(±)-4a–(±)-4h, (±)-5a and (±)-5b]. All of the synthetic compounds showed significant seed germination activities for Orobanche minor and witchweed (Striga asiatica).

Published
1999
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64. Synthetic Disproof of the Structure Proposed for Alectrol, the Germination Stimulant from Vigna unguiculata

Author

Matsui, Junichi, Bando, Masahiko, Kido, Masaru, and Takeuchi, Yasutomo

Abstract

Several compounds [(±)-3a, (±)-3b, (±)-10, (±)-11, and (±)-12] with structures related to that proposed for alectrol (3), the germination stimulant for seeds of parasitic weeds, have been synthesized. Structure (±)-3a has been solved by X-ray-crystallographic analysis. Comparison of the 1H-NMR data of the synthetic compounds with those reported for alectrol showed the proposed structure 3 to be incorrect. The synthetic products (±)-3a and (±)-3b showed significant germination stimulating activity on clover broomrape (Orobanche minor) seeds.

Published
1999
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65. Syntheses of (±)- and (+)-Sorgolactone, the Germination Stimulant from Sorghum bicolor

Author

Matsui, Junichi, Bando, Masahiko, Kido, Masaru, and Takeuchi, Yasutomo

Abstract

Syntheses of (±)-2a, the racemate of the structure proposed for sorgolactone, and its three racemic stereoisomers have been accomplished with confirmation of the stereostructures of the intermediate (±)-10 and the final product (±)-2a by X-ray analysis. Its optically active form, (3aR,8S,8bS,2'R)-(+)-2a, has also been prepared from (S)-(–)-citronellal by employing radical cyclization of 18 to 19 as the key step. Spectroscopic properties of the synthetic products are compared with those reported for natural sorgolactone. Bioassays using clover broomrape (Orobanche minor) seeds have revealed that all the stereoisomers strongly stimulate their germination.

Published
1999
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67. Tricalysiolide G, and Tricalysiols A and B : rearranged ent-Kaurane-Type and ent-Kaurane-Type Diterpenoids from the Leaves of Tricalysia dubia (Lindl.) Ohwi

Author

He, Dong-Hui, Matsunami, Katsuyoshi, Otsuka, Hideaki, Shinzato, Takakazu, Aramoto, Mitsunori, Bando, Masahiko, Takeda, Yoshio, He, Dong-Hui, Matsunami, Katsuyoshi, Otsuka, Hideaki, Shinzato, Takakazu, Aramoto, Mitsunori, Bando, Masahiko, and Takeda, Yoshio

Abstract

Three rearranged ent-kaurane diterpenes having the cafestol-type framework were isolated from the leaves of Tricalysia dubia. Two of them were found to be known diterpenoids, tricalysiolides B and C. Tricalysiolide B was isolated as colorless prisms in this experiment and its three dimensional structure was determined by X-ray crystallography. The remaining one was a new compound and named tricalysiolide G. Two new ent-kaurane-type diterpenoids, to which tricalysiols A and B were given as trivial names, were also isolated. The structures of the new compounds were elucidated from spectroscopic evidence.

75. ChemInform Abstract: Enantioselective Synthesis of the Metabolites of Vasopressin V2Receptor Antagonist OPC‐31260 via Lipase‐Catalyzed Transesterification.

Author

Matsubara, Jun, Kitano, Kazuyoshi, Otsubo, Kenji, Kawano, Yoshikazu, Ohtani, Tadaaki, Bando, Masahiko, Kido, Masaru, Uchida, Minoru, and Tabusa, Fujio

Abstract

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Published
2000
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76. Determination of the stereochemistry of (-)-koninginin A by an X-ray analysis of its synthetic sample.

Author

Mori K, Bando M, and Abe K

Subjects
Crystallography, X-Ray, Molecular Conformation, Stereoisomerism, Trichoderma chemistry, Benzoxepins chemistry, Heterocyclic Compounds, 3-Ring chemistry
Abstract

The absolute configuration of (-)-koninginin A [10-hexyl-11, 12-dioxatricyclo[7.2. 1.0<1 ,6>]dodecane-2,5-diol (1)], the antibiotic metabolite of Trichoderma koningii and T. harzianum, was determined as 1S, 2R, 5S, 6S, 9S, 10S by an X-ray crystallographic analysis of its synthetic sample coupled with the established stereochemical outcome of Sharpless asymmetric dihydroxylation used as the key reaction to prepare intermediate 4.

Published
2002
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77. Tricalysiosides A-G: rearranged ent-kauranoid glycosides from the leaves of Tricalysia dubia.

Author

He DH, Otsuka H, Hirata E, Shinzato T, Bando M, and Takeda Y

Subjects
Chromatography, Crystallography, X-Ray, Hydrolysis, Japan, Molecular Conformation, Molecular Structure, Nuclear Magnetic Resonance, Biomolecular, Plant Leaves chemistry, Stereoisomerism, Glycosides chemistry, Glycosides isolation & purification, Lactones chemistry, Lactones isolation & purification, Plants, Medicinal chemistry, Rubiaceae chemistry
Abstract

Seven rearranged ent-kaurane glycosides, named tricalysiosides A-G (1-7), were isolated from the leaves of Tricalysia dubia collected on Okinawa Island. Their C-18 and 19 methyls were found to have rearranged to form an alpha,beta-unsaturated gamma-lactone ring, with other functional groups remotely located only on C-15, -16, and -17 of the five-membered ring. Information available from various kinds of two-dimensional NMR spectra was limited and insufficient to allow total characterization of the structures. Finally, using X-ray crystallographic analysis, the structure of tricalysioside A (1) was determined to be 4-nor-18-homo-ent-kauran-4(18)-en-15beta,16beta,17-triol-3beta,19-olide 16-O-beta-D-glucopyranoside (1). On the basis of the crystal structure of 1, the structures of the other tricalysiosides (2-7) were also established.

Published
2002
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