Enhanced reactivity of secondary hydroxyl groups in the O-alkylation of carbohydrate-related primary-secondary vic-glycols. Regioselective 2-O-benzylation of 1,3:2,4-di-O-ethylidene-D-glucitol

Article abstract of DOI:10.1007/BF00704019

Partial O-alkylation of 1,3:2,4-di-O-ethylidene-D-glucitol (1a), 1,2-O-isopropylidene-3-O-methyl-α-D-glucofuranose (1b), and R-(+)-1-O-benzylglycerol (1c) with benzyl chloride in a KOH/DMSO system results in products of monoalkylation at the secondary (4a-c) and at the primary hydroxyl (2a-c) in ratios of over 95:5 (a), ca. 2:1 (b), and ca. 1:1 (c), whereas (+/-)propane-1,2-diol (1d) gives only the product of 1-O-benzylation (2d).A qualitatively similar result is observed upon O-alkylation of diols (1a-e) with 2-methoxyethanol tosylate.