peracetylation

Peracetylation is a chemical modification in which all hydroxyl groups (and in some cases amine groups) of a molecule are converted into acetate esters or acetyl amides through reaction with acetylating agents such as acetic anhydride or acetyl chloride. In carbohydrate and nucleoside chemistry, peracetylation is used to protect multiple hydroxyl groups, producing tetra-, penta-, or hexakisacetate derivatives that are more lipophilic and less reactive than the parent compounds. This protection facilitates selective reactions at non-acetylated sites and simplifies purification and analysis. Peracetylation is typically achieved under base- or catalyst-mediated conditions, commonly using excess acetic anhydride in pyridine or with catalysts such as DMAP.

Applications include preparation of protected sugars for glycosylation reactions, stabilization of reactive intermediates, and generation of derivatives that are more volatile or easier to analyze by analytical methods such as gas chromatography–mass spectrometry. Peracetylated nucleosides and amino sugars often serve as intermediates in further transformations, with deprotection steps required to reveal the native functionalities.

Limitations include a lack of chemoselectivity, potential side reactions with sensitive functional groups, and the need for careful deacetylation to restore original functionalities. Deacetylation is typically achieved by hydrolysis under basic or methanolic conditions, or enzymatically with esterases, depending on the substrate.

Safety considerations involve the use of corrosive acetylating agents and the generation of acylating byproducts; appropriate ventilation and protective equipment are recommended. Peracetylation remains a standard protecting-group strategy in carbohydrate and nucleoside synthesis, as well as a tool for analytical derivatization.