PREPARATIONS AND REACTIONS OF ALKYL ETHERS OF SOME ALDOHEXOSES

摘要

Aldohexose, such as D-glucose, D-galactose or D-mannose, reacted with acetone to give the following O-isopropylidene derivatives: 1,2;5,6-di-O-isopropylidene-D-glucofuranose (IA), 1,2;3,4-di-O-isopropylidene-D-galactopyranose (IB) or 2,3;5,6-di-O-isopropylidene-D-mannofuranose (IC). The O-isopropylidene derivative (IA similar to IC) reacted with alkyl/alkenyl halogenide to yield aldohexose ether compounds containing di-O-isopropylidene group, 3-O-alkyl-1,2;5,6-di-O-isopropylidene-D-glucofuranose (II), 6-O-alkyl-1,2;3,4-di-O-isopropylidene-D-galactopyranose (III) or 1-O-alkyl-2,3;5,6-di-O-isopropylidene-D-mannofuranoside (IV), in good yields. The Williamson ether synthesis was carried out using phase-transfer catalysis (PTC). The derived aldohexose alkyl ether containing di-O-isopropylidene group was hydrolyzed to give 3-O-alkyl-1,2-O-isopropylidene-D-glucofuranose (V) as a partial hydrolysis product; the complete hydrolysis of I similar to IV gave, as expected, 3-O-alkyl-glucopyranose (VI), 6-O-alkyl-galactopyranose (VII) or 1-O-alkyl-mannofuranoside (VIII). Further alkylation of (V) with Mel under PTC and subsequent acid hydrolysis gave 3-O-alkyl-5,6-di-O-methyl-D-glucofuranose (X). Methanolysis of III with catalytic amounts of H2SO4 gave 1-O-methyl-6-O-alkyl-D-galactofuranoside (XI). The elucidation of the galactofuranoside skeleton of (XI) was determined by means of its C-13 nuclear magnetic resonance spectra. The O-alkyl aldohexoses, e.g., X and: XI, were evaluated and found to be emulsifiers. [References: 16]