Stereoselective Synthesis of 5-Thio-β-L-Fucopyranosyl Phosphate

The fucosyltransferase-catalyzed 5-thiofucosylation reaction suffered from limitations in the β-selective synthesis of GDP-5-thiofucose, a donor substrate. We found that the use of electronegatively-substituted benzoate groups for 5-thiofucose protection improved the β-selectivity in the phosphorylation step. We thus achieved the synthesis of 5-thio-β- L-fucosyl phosphate in 50% yield from 5-thiofucose, using the 3,5-dinitrobenzoyl group.