ENHANCED REACTIVITY OF SECONDARY HYDROXYL-GROUPS IN THE O-ALKYLATION OF CARBOHYDRATE-RELATED PRIMARY-SECONDARY VIC-GLYCOLS - REGIOSELECTIVE2-O-BENZYLATION OF 1,3-2,4-DI-O-ETHYLIDENE-D-GLUCITOL

Partial O-alkylation of 1,3:2,4-di-O-ethylidene-D-glucitol (1a), -O-is opropylidene-3-O-methyl-alpha-D-glucofuranose (1b), and R-(+)-1-O-benz ylglycerol (1c) with benzyl chloride in a KOH/DMSO system results in p roducts of monoalkylation at the secondary (4a-c) and at the primary h ydroxyl (2a-c) in ratios of over 95:5 (a), -2:1 (b), and -1:1 (c), whe reas (+/-)propane-1,2-diol (1d) gives only the product of 1-O-benzylat ion (2d). A qualitatively similar result is observed upon O-alkylation of diols (la-e) with 2-methoxyethanol tosylate.