Preparation of Long‐Chain Alkyl D‐Glucosides by Alcoholysis of 1,2:5,6‐Di‐O‐Isopropylidene‐α‐D‐Glucofuranose

Abstract

AbstractThe acid‐catalysed conversion of 1,2:5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (1) in 1‐butanol was studied using HPLC, 1HNMR, and 13C NMR. The course of the reaction, which involved six compounds containing isopropylidene groups, was elucidated. Eventually an anomeric mixture of butyl D‐glucosides was formed. Sulfuric, methanesulfonic, and tetrafluoroboric acid, an ion‐exchange resin (–SO3H), and a silica‐alumina catalyst showed different selectivities and catalytic activities. The ion‐exchange resin was the catalyst of choice, yielding up to 90% butyl D‐glucoside. Conversion of 1 in 1‐octanol gave a reaction mixture from which octyl α‐D‐glucopyranoside could be crystallised in 30% yield. An almost quantitative yield of the latter compound, however, was obtained by recycling the mother liquor. This procedure also avoids wasting of the ionexchange resin catalyst and the excess of octanol. 1‐Decanol and 1‐dodecanol gave crystalline α‐D‐glucopyranosides by the same method.