title: Room-temperature ionic liquids enhanced green synthesis of β-glycosyl 1-ester.
abstract: We herein report an efficient synthesis of β-glycosyl 1-ester in room-temperature ionic liquids (RTILs) promoted via silver salt and quaternary ammonium salt (PTC) with good or excellent yields. All products were isolated exclusively as the β-anomers. Four different RTILs, eight metal salts and four quaternary ammonium salts were screened in the glycosylation reaction. The synergistic effect of C6mim·OTf, Ag2O and tetrabutylammonium iodine gave the best results. Their promotion to the system was integral. Thorough study provided insight into the catalytic activity of ionic liquid structure, metal salts and quaternary ammonium salt to these reactions. It is worth mentioning that the yield of aliphatic compound 2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl butyrate (3l) was highly improved when using C6mim·OTf as solvent compared with the normal volatile solvents under the same catalysts. This green approach has been proved to be practical and compatible with a wide range from aliphatic to aromatic substrates.
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou 310027, PR China. Electronic address: hnzzcyl@hotmail.com.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Department of Chemistry, Zhejiang University, Hangzhou 310027, PR China.
authors.forename: Minghan
authors.initials: M
authors.lastname: Xu
authors.affiliation: Carbohydrate Chemistry and Biotechnology Jiangnan University Key Laboratory of Ministry of Education, Wuxi 214122, PR China.
authors.forename: Weirong
authors.initials: W
authors.lastname: Yao
authors.affiliation: Zhejiang Provincial Key Lab for Chem. & Bio. Processing Technology of Farm Produces, Hangzhou 310023, PR China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Mao
mesh_terms: D002384:Catalysis; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012492:Salts / Q000138:chemical synthesis* / Q000737:chemistry; D012834:Silver / Q000737:chemistry; D013696:Temperature
chemical_list: D052578:Ionic Liquids; D000644:Quaternary Ammonium Compounds; D012492:Salts; D012834:Silver; C009405:tetrabutylammonium
keywords: Glycosyl bromide; Glycosyl ester; Green glocosylation; Ionic liquid; Silver oxide