Acetyl group, removal from carbohydrate

Candida cylindracea, phosphate buffer pH 7, Bu20. The 6-0-acetyl of Q -methyl peracetylglucose was selectively removed. Porcine pancreatic lipase will also hydrolyze acetyl groups from carbohydrates. These lipases are not specific for acetate since they hydrolyze other esters as well. In general selectivity is dependent on the ester and the substrate. ... 

The hydroxyl groups of the carbohydrates are protected as acetyl or benzoyl ester which, upon cleavage of the completed glycopeptide from the solid support, are readily removed by treatment with sodium methoxide or hydrazine. 

A new method for iV-deacetylation of carbohydrates - particularly polysaccharides containing 2-acetamido-2-deoxyhexoses - involved treatment with sodium hydroxide in aqueous DMSO at ca. 100 °C in the presence of sodium thiophenolate as an oxygen scavenger and catalyst. The iV-benzoyl group was selectively removed from benzyl 4,6-di-0-acetyl-2-benzamido-3-0-benzyl-2-deoxy-a-D-glucopyranoside by the sequence of reactions shown in Scheme 34. ... 

Further chain extension and Pd (O)-catalyzed detachment from the resin gave the protected glycoundecapeptide. After acidolytic removal of the side-chain protecting groups the 0-acetyl groups and the methyl ester were cleaved by carefully optimized treatment with dilute aqueous NaOH in MeOH and aqueous NaOH (pH 11.5) ( 71). At pH < 11.5 no methyl ester cleavage was achieved whereas above this pH epimerization and p-elimination of the carbohydrate occurred. 

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