| Sumario: | Hydrogenolysis of 2, 3, 5-tri-O-benzoyl-6-O-trityl-D-galactono-1, 4-lactone (2) gave the corresponding 3-deoxy-D-xyIo-hexono-l, 4-lactone derivative (3), which on treatment with HBr in acetic acid afforded 2, 5-di-O-benzoyl-6-bromo-3, 6-dideoxy-D-xylo-hexono 1, 4-lactone (4). Hydrogenation of 4 led to 3, 6-dideoxy-D-xylo-hexono-1, 4-lactone dibenzoate (6). The overall yield of 6 from D-galactono-1, 4-lactone (1) was about 59%. Alternatively, compound 6 was prepared (67% overall yield from 1) by hydrogenolysis of 6-bromo-6-deoxy-D-galactono-l, 4-lactone tribenzoate (5), obtained by treatment of 2 with HBr in dry dichloromethane. Diisoamylborane reduction of 6 gave an anomeric mixture of 2, 5-di-O-benzoyl-3, 6-dideoxy-a, p-D-xylo-hexofuranose (7), which on O-debenzoylation afforded 3, 6-dideoxy-D-xylo-hexose (abequose, 8) whose tautomeric equilibrium was studied by 13C NMR spectroscopy. Acetylation of 7 gave the 1-O-acetyl derivative (9) mainly in the βanomeric configuration. Tin (IV) chloride promoted glycosylation of 9 with methanol and ethanol afforded stereoselectively methyl (10) and ethyl 2, 5-di-O-benzoyl-3, 6-dideoxy-p-D-xylo-hexofuranoside (11), respectively. © 1991, Taylor & Francis Group, LLC. All rights reserved.
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