Boronic esters as protective groups in carbohydrate chemistry: processes for acylation, silylation and alkylation of glycoside-derived boronates

Boronic esters are employed in streamlined protocols for protection, functionalization and deprotection of glycosides, avoiding isolation and purification of intermediates.

Boronate derivatives of functionally diverse catechols: stability studies

Benzeneboronate of catecholic carboxyl methyl esters, N-acetyldopamine, coumarin and catechol estrogens were prepared as crystalline derivatives in high yield. Related catechol compounds with extra polar functional group(s) (OH, NH2) do not form or only partially form unstable cyclic boronate derivatives.

Activation of Sugar Hydroxyl Groups Prior to Glycosylation

The hydroxyl groups of phenols and alcohols, including sugar alcohols, may be activated to make them more susceptible to glycosylation, but frequently activation is not formally carried out before such substitution. The present review considers methods that can be used to bring about hydroxyl group activation and thereby to facilitate glycosylation.

Synthesis of methyl alpha- and beta-D-xylopyranoside-5-18O

Methyl alpha- and beta-D-xylopyranoside-5-18O (5 and 6) were prepared by way of oxygen exchange between 18O-water and the periodate-oxidation product (1) obtained from 1,2-O-isopropylidene-alpha-D-glucofuranose. The isotopic enrichment of 5 and 6 was determined by hydrolysis of each to D-xylose-5-18O (3), conversion of the sugar into 1,2,3,4-tetrakis-O-(tert-butyldimethylsilyl)-beta-D-xylopyranose-5-18O (7), and determination of the 18O content of the latter by use of a quadrupole, mass spectrometer.