Regioselective Acylation Of Carbohydrates Research Articles

Exploring Cooperative Effects in Oxidative NHC Catalysis: Regioselective Acylation of Carbohydrates.

The utility of oxidative NHC catalysis for both the regioselective and chemoselective functionalization of carbohydrates is explored. Chiral NHCs allow for the highly regioselective oxidative esterification of various carbohydrates using aldehydes as acylation precursors. The transformation was also shown to be amenable to both cis/trans diol isomers, free amino groups, and selective for specific sugar epimers in competition experiments. Efficiency and regioselectivity of the acylation can be improved upon using two different NHC catalysts that act cooperatively. The potential of the method is documented by the regioselective acylation of an amino-linked neodisaccharide.

Enzymatic acylation of levoglucosan in acetonitrile and ionic liquids

The regioselective acylation of carbohydrates is of great interest in many industrial fields. Levoglucosan (1,6-anhydroglucopyranose), an anhydro-sugar easily obtainable through the pyrolytic treatment of cellulose, can be used as an excellent alternative feedstock to get chemicals of interest from renewable resources. Levoglucosan has been acylated in good yields with diverse acyl donors, such as vinyl esters and carboxylic acids with long and short chains in alternative green solvents: CH3CN, a traditional organic solvent with low ecotoxicity, and ionic liquids. The surfactant properties of 4-O-lauryl-levoglucosan have been evaluated and resulted in the range of oil soluble emulsifiers.

Selective Organocatalytic Ring-Opening Polymerization: A Versatile Route to Carbohydrate-Functionalized Poly(ε-caprolactones)

Cationic catalysis using simple carboxylic acids to combine the ring-opening polymerization of ε-caprolactone and the regioselective acylation of carbohydrates has been investigated. l-Lactic acid catalyzed the acylation of methyl β-d-glucopyranoside and sucrose with ε-caprolactone in high yield by bulk polymerization at 120 °C. The main products were regioselectively acylated on the primary hydroxyl groups of the carbohydrate end groups. The overall conversion to methyl β-d-glucopyranoside-functionalized poly(ε-caprolactone) was more than 90%, Mw 2000 and polydispersity index 1.5, with one major product methyl 6-O-poly(ε-caprolactone)-β-d-glucopyranoside, in agreement with the corresponding Candida antarctica lipase B-catalyzed acylation.

ChemInform Abstract: Regioselective Acylation of Carbohydrates with 1‐Acyloxy‐1H‐ benzotriazoles.

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Regioselective Acylation of Carbohydrates with 1-Acyloxy-1H-benzotriazoles

Acylation of representative carbohydrate derivatives was accomplished with in situ generated 1-acyloxy-1H-benzotriazoles. The observed high regioselectivity, mild reaction conditions and convenient work-up make the presented one-pot procedure generally applicable and more advantageous than acylations with previously introduced reagents, including N-acylimidazoles

An improved procedure for regioselective acylation of carbohydrates: novel enzymatic acylation of α-D-glucopyranose and methyl α-D-glucopyranoside

6-O-Monoesters of α-D-glucopyranose and methyl α-D-glucopyranoside have been prepared with high yields through a novel enzymatic reaction using oxime esters as acyl transfer agents.