A FACILE SYNTHESIS OF 5-THIO-L-FUCOSE AND 5-THIO-D-ARABINOSE FROM D-ARABINOSE

摘要

5-Thio-L-fucopyranose tetraacetate was synthesized in 11 steps from 5-O-trityl-D-arabino-furanose or D-arabinose diethyl dithioacetal by one-carbon elongation at C-5. Highly diastereoselective addition of MeLi in ether to a 1,2-O-isopropylidene-beta-D-arabino-pentodialdo-1,4-furanose derivative was achieved to give the corresponding 6-deoxy-beta-D-altrofuranose isomer in good yield. A sulfur atom was introduced at C-5 of 6-deoxy-D-altrofuranose derivatives via substitution of a 5-tosylate with KSAc in HMPA with inversion of configuration, giving 5-thio-L-fucopyranose. A 3-O-substituted-L-fucose derivative was also prepared from 6-deoxy-beta-D-altrofuranose derivatives. 5-Thio-D-arabinopyranose tetraacetate, the 5-demethyl analog of 5-thio-L-fucose, was also synthesized from 5-O-trityl-D-arabinofuranose in 5 steps. 5-Thio-D-arabinose showed weak inhibitory activity against a-L-fucosidase from bovine kidney (K-i = 0.77 mM). [References: 21]