2,2-Dimethyl-propionic acid (2R,3R,3aR,6S,7R,7aR)-2-(4-acetylamino-2-oxo-2H-pyrimidin-1-yl)-6-methoxy-7-[3-(2,2,2-trichloro-acetyl)-ureido]-hexahydro-furo[3,2-b]pyran-3-yl ester

(2R,3R,3aR,6S,7R,7aR)-7-azido-2-(2',4'-dioxo-3',4'-dihydro-2H-pyrimidin-1'-yl)-6-methoxy-3-pivaloyloxy-hexahydrofuro[3,2-b]pyran