Counterion-directed regioselective acetylation of octyl beta-D-glucopyranoside.

[reaction: see text] The DMAP-catalyzed acetylation of octyl beta-D-glucopyranoside with a series of acetylating agents has been investigated. The nature of the counterion of the catalytic DMAP-acetyl complex dramatically influences the outcome of the reaction, indicating that the deprotonation of the transition state is controlling the reaction. Noncovalent interactions of the acetate ion with the substrate seem to direct the acetylation toward secondary hydroxyl groups.