Jun-ichi Onodera
Yamagata University
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Featured researches published by Jun-ichi Onodera.
Carbohydrate Research | 1998
Toshihiro Kumazawa; Nobutaka Asahi; Shigeru Matsuba; Shingo Sato; Kimio Furuhata; Jun-ichi Onodera
Abstract Treatment of β- d -C-glucopyranosyl phloroacetophenone in water in the presence of a catalytic amount of p-TsOH afforded a spiroketal product. This is the first demonstration of ring conversion in aryl C-glycoside. The structure of the product was determined by 1H-1H COSY, HMQC, HMBC, NOESY, and single crystal X-ray analysis of the corresponding acetylated compound.
Carbohydrate Research | 1999
Toshihiro Kumazawa; Yasuyuki Akutsu; Shigeru Matsuba; Shingo Sato; Jun-ichi Onodera
Abstract 2′- O -Acetyl C -glycosylic compounds ( C -glycosides) were prepared via regioselective acetyl transfer from aglycons to sugar moieties with silica gel in the presence of unprotected primary and secondary hydroxyl groups.
Carbohydrate Research | 2000
Toshihiro Kumazawa; Shingo Sato; Shigeru Matsuba; Jun-ichi Onodera
The reaction of 2,3,4-tri-O-benzyl-alpha-L-rhamnopyranosyl fluoride (6-deoxy-2,3,4-tri-O-benzyl-alpha-L-mannopyranosyl fluoride) with 2,4-dibenzylphloroacetophenone, in the presence of boron trifluoride.diethyl etherate, afforded both the 3-C-alpha-L- and the 3-C-beta-L-rhamnopyranosylphloroacetophenone derivatives. The 3-C-alpha-L-rhamnoside was produced as a major product, while the 3-C-beta-L-rhamnoside was produced as a minor product via anomerization of the 3-C-alpha-L-rhamnoside. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-alpha-D-mannopyranosyl fluoride with 2,4-dibenzylphloroacetophenone afforded both the 3-C-alpha-D- and the 3-C-beta-D-mannnopyranosylphloroacetophenone derivatives under identical conditions. The 3-C-beta-D-mannoside was produced as a major product via anomerization of the 3-C-alpha-D-mannoside during the reaction. These differences in composition result apparently from the magnitude of the 1,3-diaxial interactions between the C-3 and C-5 positions in these sugar moieties.
Carbohydrate Research | 2000
Toshihiro Kumazawa; Masami Chiba; Shigeru Matsuba; Shingo Sato; Jun-ichi Onodera
Treatment of 3-C-beta-D-galactopyranosylphloroacetophenone in hot water with a catalytic amount of p-toluenesulfonic acid afforded a spiroketal compound as the main product. The chirality of the spiro carbon of the product was R, which is the opposite of the spiroketal obtained by the conversion of 3-C-beta-D-glucopyranosyl phloroacetophenone under identical conditions. The structure was determined by 1H-1H COSY, 1H-13C COSY, NOESY and HMBC spectroscopy.
Carbohydrate Research | 1997
Toshihiro Kumazawa; Mitsuo Ishida; Shigeru Matsuba; Shingo Sato; Jun-ichi Onodera
Abstract Bis-glycosylation of 3,5-dibenzyloxyphenol with 2,3,4,6- tetra -O- benzyl-α- d -glucopyranosyl fluoride in a two-step sequence produced the bis-glucosylated product, 3,5- dibenzyloxy -2,6- bis -(2,3,4,6- tetra -O- benzyl-β- d -glucopyranosyl)phenol . Subsequent hydrogenolytic debenzylation and acetylation gave the undeca-O-acetyl derivative, which, when subjected to a Friedel-Crafts acylation with borontrifluoride-acetic acid, gave the 4-C-acetyl target compound, 1-[3,5- bis -(2,3,4,6- tetra -O- acetyl-β- d -glucopyranosyl)-2,4,6-trihydroxyphenyl]ethanone .
Carbohydrate Research | 2001
Shingo Sato; Toshihiro Kumazawa; Shigeru Matsuba; Jun-ichi Onodera; Masaaki Aoyama; Heitaro Obara; Hitoshi Kamada
Glycosylation of the nitroxyl radicals, 4-acetoxy-2,2,6,6-tetramethylpiperidin-1-oxyl (4-acetoxy-TEMPO) and 3-carbamoyl-2,2,5,5-tetramethylpyrollin-1-oxyl (3-carbamoyl-PROXYL) with peracetylglycosyl fluoride as the glycosyl donor, in the presence of boron trifluoride diethyl etherate (BF(3) x OEt(2)) and an amine base afforded the corresponding hydroxylamine-O-glycosides in 25-100% yields.
Journal of Magnetic Resonance | 2003
Kôichi Fukui; Tomohiro Ito; Mika Tada; Masaaki Aoyama; Shingo Sato; Jun-ichi Onodera; Hiroaki Ohya
A multiband (L-band, 0.7GHz; X-band, 9.4GHz; and W-band, 94GHz) electron paramagnetic resonance (EPR) study was performed for two glycosidated spin probes, 4-(alpha,beta-D-glucopyranosyloxy)-TEMPO (Glc-TEMPO) and 4-(alpha,beta-D-lactopyranosyloxy)-TEMPO (Lac-TEMPO), and one non-glycosylated spin probe, 4-hydroxy-TEMPO (TEMPOL), where TEMPO=2,2,6,6-tetramethyl-1-piperidinyloxyl, to characterize fundamental hydrodynamic properties of sugar-connected spin probes. The linewidths of these spin probes were investigated in various concentrations of sucrose solutions (0-50wt%). The multiband approach has allowed full characterization of the linewidth parameters, providing insights into the molecular shapes of the spin probes in sucrose solution. The analysis based on the fast-motional linewidth theory has yielded anisotropy parameters of rho(x) approximately 2.6 and rho(y) approximately 0.9 for Glc-TEMPO, and rho(x) approximately 4.2 and rho(y) approximately 0.9 for Lac-TEMPO. These values indicate that the glycosidated spin probes have a prolate-type molecular shape elongated along the x-axis (NO(rad) axis) with Lac-TEMPO elongated more remarkably, consistent with their molecular structures. The interaction parameters k (the ratios of the effective hydrodynamic volumes to the real ones) corrected for the difference in molecular shape have been estimated and found to have the relation k(TEMPOL)<k(Glc-TEMPO) approximately k(Lac-TEMPO). This agrees with the expectation that glycosidated spin probes can have stronger hydrogen bonding to water. Glycosidated spin probes are expected to be useful for probing sugar-involving interactions, which commonly occur in biological systems. Thus this study will provide an indispensable basis for such spin-probe studies.
Carbohydrate Research | 2002
Toshihiro Kumazawa; Kanako Onda; Hayato Okuyama; Shigeru Matsuba; Shingo Sato; Jun-ichi Onodera
The reaction of 2,3,4-tri-O-benzyl-6-deoxy-alpha-D-glucopyranosyl fluoride, 2,3,4,6-tetra-O-benzyl-alpha-D-allopyranosyl fluoride, and 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl fluoride with 2,4-di-O-benzylphloroacetophenone, in the presence of boron trifluoride diethyl etherate, afforded, respectively, the corresponding 3-C-beta-D-glycopyranosylphloroacetophenone derivatives exclusively in anomerically pure form. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-alpha-D-gulopyranosyl fluoride with 2,4-di-O-benzylphloroacetophenone afforded both the 3-C-beta-D-gulopyranosylphloroacetophenone derivative (4C(1) conformation) as the major product and the 3-C-alpha-D-gulopyranosylphloroacetophenone derivative (1C(4) conformation) as the minor product under identical conditions. Including the previously prepared C-glycosylphloroacetophenone derivatives that contain 3-C-beta-D-glucosyl, 3-C-beta-D-xylosyl, 3-C-beta-2-deoxy-D-arabino-hexosyl, 3-C-beta-D-galactosyl, 3-C-beta-L-arabinosyl, and 3-C-alpha-L-arabinosyl moieties, the conformation is dictated primarily by the preference of the bulky aromatic aglycon to orient equatorially, due to the strong repulsion of the aglycon. The anomerization is directed secondarily by the presence of 1,3-diaxial interactions in the sugar moiety.
Carbohydrate Research | 2001
Toshihiro Kumazawa; Takayuki Kimura; Shigeru Matsuba; Shingo Sato; Jun-ichi Onodera
The treatment of unprotected mono-C-beta-D-glucopyranosylphloroacetophenone with a cation-exchange resin in anhydrous acetonitrile afforded both a phloroacetophenone and a di-C-beta-D-glucopyranosylphloroacetophenone. Treatment of an unprotected mono-C-(2-deoxy-beta-D-arabino-hexopyranosyl)phloroacetophenone (mono-C-2-deoxy-beta-D-glucopyranosylphloroacetophenone) also afforded both the aglycon and di-C-(2-deoxy-beta-D-arabino-hexopyranosyl)phloroacetophenone. The reaction mixtures were acetylated, and the structures of the isolated products were determined by NMR spectroscopy. This is the first demonstration of the formation of a di-C-glycosyl compound during the chemical cleavage of the C-C linkage between the sugar and the aglycon in an aryl C-glycosyl derivative.
Supramolecular Chemistry | 2006
Shingo Sato; Hiroaki Iijima; Norihiro Haga; Kohbun Osono; Hitoshi Mizuguchi; Tatsuro Kijima; Jun-ichi Onodera
The Calix[4]arene 1 including two alternately arranged phloroglucinols and p-tert-butylphenols was synthesized via the “3+1” coupling procedure, and its pKa values were estimated to be 3–4 and 7.5, while those of the other six phenolic hydroxyls were approximately 11. Its UV–vis spectrum at pH 11 and 1H and 13C NMR spectra in NaOD-D2O solution (pH 12.8) showed a dramatic change like those of the phloroglucinol when compared to those in acidic or neutral solution, which suggests a change in the phloroglucinol moiety to the keto-form. During the solvent extraction for alkali metal species using 1, Li+ was only extracted in the low yield of 15% at pH 11. The cyclic voltammetry study of 1 was used to compare it with the phloroglucinol and p-tert-butylphenol. The redox potential of the corresponding two phloroglucinols was observed in 1.