pentyl (1-((2R,3R,4S,5R)-4-(((2R,3R,4S,5R)-3,4-dihydroxy-5-methyltetrahydrofuran-2-yl)oxy)-3-hydroxy-5-methyltetrahydrofuran-2-yl)-5-fluoro-2-oxo-1,2-dihydropyrimidin-4-yl)carbamate