- Copper-Catalyzed Anomeric O-Arylation of Carbohydrate Derivatives at Room Temperature
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Direct and practical anomeric O-arylation of sugar lactols with substituted arylboronic acids has been established. Using copper catalysis at room temperature under an air atmosphere, the protocol proved to be general, and a variety of aryl O-glycosides have been prepared in good to excellent yields. Furthermore, this approach was extended successfully to unprotected carbohydrates, including α-mannose, and it was demonstrated here how the interaction between carbohydrates and boronic acids can be combined with copper catalysis to achieve selective anomeric O-arylation.
- Verdelet, Tristan,Benmahdjoub, Sara,Benmerad, Belkacem,Alami, Mouad,Messaoudi, Samir
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p. 9226 - 9238
(2019/08/12)
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- Chemical synthetic method for beta-arbutin
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The invention provides a chemical synthetic method for beta-arbutin, which includes: 1) performing a reaction to pentaacetyl-beta-D-glucose with a 70% hydrofluoric acid pyridine solution at 10-30 DEGC to obtain tetraacetyl-alpha-fluoroglucose; 2) performing a reaction to the tetraacetyl-alpha-fluoroglucose with p-hydroxyacetophenone in a mixed solvent under catalysis of tetrabutylammonium bromidewith Ca(OH)2 being an accelerant at 20-30 DEG C to prepare p-acetylphenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside; 3) performing a reaction to the p-acetylphenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside with 40% peroxyacetic acid in an organic solvent at 5-20 DEG C to obtain p-acetoxylphenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside; 4) performing a reaction to the p-acetoxylphenyl-2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside at 15-25 DEG C in the presence of anhydrous methanol-sodium methoxide to obtain the beta-arbutin. The method is high in yield, low in cost, gentle in conditions and less in emission of waste liquid, waste gas and waste solids, and is suitable for industrial production.
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Paragraph 0007; 0010; 0011; 0015
(2019/01/08)
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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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