Anomeric Deacetylation Research Articles

Selective Anomeric Deacetylation of Per-Acetylated Carbohydrates Using (i-Pr)3Sn(OEt) and Synthesis of New Derivatives

In this study natural carbohydrates such as glucose, galactose, xylose, fructose andlactose, are acetylated by acetic anhydride and sodium acetate catalyst. Anomeric configuration is deacetylated by (i-Pr)3Sn(OEt)as a catalyst, an easy synthetic regioselective deacetylation of full acetylated carbohydrates using (i--Pr)3Sn(OEt) is described. The acetylated carbohydrates reacted with HBr (solution in AcOH, 32 wt.%) for the bromination of anomeric position. The synthesis oxazaphosphorine, and bromo hexa alkyl Methylsulfonate derivatives from anomeric position of carbohydrates was reacted. FT IR, 1H, 13C NMR, 31PNMR spectroscopy techniques were employed to examine the synthesized compounds.

Generalising a Simple Methodology for the Regioselective Anomeric Deacetylation of Carbohydrates

AbstractThe use of methylamine to deprotect 1‐O‐acetyl protected carbohydrates has only attracted limited interest in the literature. Demonstrated here is an approach that is able to be generalized for a wide variety of carbohydrate scaffolds which results in a high yielding, simplified, practical, expedient and clean method to prepare hemiacetals from 1‐O‐acetyl protected carbohydrates.

Hafnium(IV) triflate as a potent catalyst for selective 1-O-deacetylation of peracetylated saccharides

An efficient method for selective anomeric deacetylation of peracetylated mono-, di-, and trisaccharides has been developed by using 2 mol% Hf(OTf)4 as catalyst in acetonitrile. Employment of ultrasonic irradiation could significantly accelerate the reaction rate. Mechanistic study confirmed the hydrolysis nature of this reaction, and NMR experimental data suggested that multiple peracetylated saccharide molecules may ligate to Hf(IV) cation primarily via the anomeric acetate to promote its specific hydrolysis.

Synthesis of an α-Amylase Inhibitor: Highly Stereoselective Glycosidation and Regioselective Manipulations of Hydroxyl Groups in Carbohydrate Derivatives

Here, we describe the efficient synthesis of α-amylase inhibitor 1. To introduce the most expensive C ring unit at a late stage in the synthesis, we developed 1,2-cis-O-glycosidation of AB and C ring intermediates. Taking advantage of the effect of non-neighboring protecting groups, reaction solvents, and temperature for the glycosidation led to high stereoselectivity and high yield of the 1,2-cis-glycoside product bearing the API skeleton. We also explored protection and deprotection methods for regioselective manipulation of hydroxyl groups in A and B ring intermediates. One-pot benzylation of the 2,3-hydroxyl groups of d-glucose under phase-transfer conditions and regioselective anomeric deacetylation with N-methylpiperazine were developed for the syntheses of A, B, and AB ring intermediates. Thus, the efficiency of the process was dramatically improved. The raw material cost of API was reduced to approximately one-third that of the original route, and the total process was decreased by six steps.

Microwave-Assisted Anomeric Deacetylation of Ribofuranoses with Fe(III) Reagents

Treatment of protected furanoses with FeCl3·6H2O in acetonitrile with microwave irradiation provides an efficient and mild protocol for regioselective removal of anomeric O-acetyl group. This method features cost efficient reagents, simple procedures, and high yields. The experimental results proved that microwave irradiation could notably shorten the reaction time and increase the product yield compared to the conventional thermal heating condition.

Selective anomeric deacetylation using zinc acetate as catalyst

AbstractAn alternative method has been developed for the anomeric deacetylation of fully acetylated carbohydrate derivatives using zinc acetate dihydrate as a catalyst in methanol under mild conditions. The experimental simplicity, low cost, acceptable yield, use of a readily handled acidic catalyst, and the environmentally benign nature are some of the advantages of this method.

ChemInform Abstract: Regioselective Green Anomeric Deacetylation Catalyzed by Lanthanide Triflates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Regioselective green anomeric deacetylation catalyzed by lanthanide triflates

Lanthanide triflates, especially Nd(OTf) 3, efficiently catalyze the regioselective transesterification of anomeric acetates. This method offers an efficient solution for the otherwise difficult removal of methyl uronates anomeric acetates as well as a green alternative to published protocols since the lanthanide catalysts are non-toxic and may be easily recycled and reused.

Isolation, Synthesis and Derivatization of Xylodextrins

AbstractA series of xylodextrins has been produced by enzymatic or hydrothermal degradation of industrial xylans. For further synthetic use, the oligomers were converted into per‐O‐acetylated xylooligomers which were separated by silica gel chromatography to furnish preparative amounts of xylobiose up to xylopentaose. In a model reaction, selective anomeric deacetylation and treatment with trichloroacetonitrile furnished a xylobiosyl donor, which was converted into the β‐methyl glycoside. In addition, methyl β‐D‐xylopyranoside was transformed into a suitable glycosyl acceptor via tosylation followed by a double displacement reaction at O‐4, allowing for further chain elongation and modification at the reducing xylopyranosyl unit.

An Alternative Method for Anomeric Deacetylation of Per‐acetylated Carbohydrates

AbstractAn alternative method for anomeric deacetylation of fully acetylated carbohydrates has been developed using imidazole in methanol.

Regioselective Anomeric Deacetylation of Peracetylated Glycopyranoses.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Regioselective Anomeric Deacetylation of Peracetylated Glycopyranoses

A simple and mild method for regioselective anomeric deacetylation of peracetylated glycopyranoses using copper(II) acetate dihydrate and methanol/water (9 : 1) is described.

Synthesis of 2,4-dinitrophenyl glycosides of d-xylobiose and d-mannobiose

d-Xylobiose hexaacetate and d-mannobiose octaacetate were obtained from xylan and mannan digests, respectively, by acetylation followed by chromatographic separation. Selective anomeric deacetylation of each peracetate, followed by 2,4-dinitrophenylation and subsequent de-protection gave 2,4-dinitrophenyl β- d-xylobioside and 2,4-dinitrophenyl α- and β- d-mannobiosides, respectively. The tetra-acetates of 2,4-dinitrophenyl α- and β- d-mannopyranoside were similarly obtained.

ChemInform Abstract: A Novel, Regio‐ and Highly Stereoselective Anomeric Deacetylation of 2‐ Amino Sugar Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A novel regio- and highly stereoselective anomeric deacetylation of 2-aminosugar derivatives

Silica gel-mediated anomeric deacetylation of per-acetylated 2-amino-2-deoxy-glycopyranose derivatives in methanol constitutes a mild and inexpensive protocol for the selective deprotection of these relevant carbohydrate templates. The reaction proceeds with high stereoselectivity and with an almost complete avoidance of by-products.