Reaction of 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose (I) with trimethylsilyl cyanide in the presence of boron trifluoride gave nitrile (II), which was treated with liquid hydrogen sulfide and DMAP to yield thioamide (III). Condensation of this thioamide with bromoketone (IV) in acetonitrile afforded the thiazole derivative (V). Hydrolysis of the benzoate esters of (V) using sodium methoxide in methanol, followed by protection of the resulting 2,3-diol with acetone and triethyl orthoformate produced the corresponding isopropylidene ketal (VI). Treatment of the primary alcohol group of (VI) with sulfamoyl chloride gave rise to the sulfamate ester (VII). Further condensation of (VII) with N-Boc-L-leucine furnished (IX). The Boc and isopropylidene groups of (IX) were finally eliminated with trifluoroacetic acid to provide the title compound.