- Phenyl glycosides – Solid-state NMR, X-ray diffraction and conformational analysis using genetic algorithm
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The X-ray structures of 2,6-dimethylphenyl and phenyl 2,3,4,6-tetra-O-acetyl β-glucosides (1 and 3) and phenyl α-mannoside (6) were obtained. The independent part of the unit cell of the glycosides 1 and 6 was formed by one molecule, and for the glucoside 3, two molecules in the crystal cell were observed. In deacetylated glycosides 4 and 6 the crystal structure was established by a hydrogen bond network formed between the sugar hydroxyls and solvent molecules. The 13C CPMAS NMR spectra of aryl glycosides 1–6 were analysed. In the spectrum of 3, doubling of the C4 aryl signal was observed which confirmed the presence of two independent molecules in the solid sample. The GAAGS (Genetic Algorithm-Assisted Grid Search) method was used to determine the low-energy conformers of α-mannosides and β-glucosides. The orientation of the aryl pendant group was calculated using Molecular Mechanics (MMFF94) as well as Quantum Mechanics theory (DFT, B3LYP/6-31 + G(d,p)).
- Wa?ejko, Piotr,Bukowicki, Jaros?aw,Dobrzycki, ?ukasz,Socha, Pawe?,Paradowska, Katarzyna
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- TEMPO-Mediated Regiospecific Oxidation of Glucosides to Glucuronides
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A TEMPO/hypochlorite/bromide oxidant has been used for the conversion of aryl and steroidal glucosides to the corresponding glucuronide conjugates in good (48-74%) yield. An isoflavone glucoside failed to undergo this transformation.
- Desai, Rakesh N.,Blackwell, Len F.
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p. 1981 - 1984
(2007/10/03)
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- Structure and reactivity of glycosides: IV. Koenigs-Knorr synthesis of aryl β-D-glucopyranosides using phase-transfer catalysts
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A series of acetylated aryl β-D-glucopyranosides were prepared in 12-63% yields from tetra-O-acetyl-α-D-glycopyranosyl bromide and phenols containing acyl, formyl, and hydroxy substituents, and also from sterically hindered phenols in the two-phase system chloroform-aqueous alkali in the presence of triethylbenzylammonium chloride. Hydroxyethylated sucrose and dibenzo-18-crown-6 do not behave as phase-transfer catalysts in glycosylation of phenols. 2001 MAIK "Nauka/Interperiodica".
- Pavlov,Sokolov,Zakharov
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p. 1811 - 1814
(2007/10/03)
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- Novel Synthesis of Aryl 2,3,4,6-Tetra-O-acetyl-D-glucopyranosides
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The glucosidation of phenols with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl fluoride in the presence of BF3*OEt2 to give, predominantly, α-anomers has been studied.In the presence of an amine base, 1,1,3,3-tetramethylguanidine, however, enhanced β-selectivity was achieved.The former reaction provides a novel and useful synthesis of aryl 2,3,4,6-tetra-O-acetyl-α-D-glucopyranoside whilst the latter is effective for the glycosidation of relatively hindered phenols.
- Yamaguchi, Masahiko,Horiguchi, Akira,Fukuda, Akira,Minami, Toru
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p. 1079 - 1082
(2007/10/02)
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