Abstract Mixtures of peracetylated β- l -arabinopyranose 1,2-(alkyl orthoacetates) and the corresponding α- l -arabinopyranosides, in ratios as high as 1:1.3, have been obtained from primary, secondary, and tertiary alcohols and 2,3,4-tri- O -acetyl-β- l -arabinosyl bromide, by reaction in dichloromethane-diethyl ether (3:1) in the presence of silver oxide and anhydrous calcium sulfate. Orthoester formation