2,2-Dimethyl-propionic acid (2S,4aR,5aR,6R,7R,8aR,9S,9aR)-7-(4-acetylamino-2-oxo-2H-pyrimidin-1-yl)-2-phenyl-9-[3-(2,2,2-trichloro-acetyl)-ureido]-octahydro-furo[2',3':5,6]pyrano[3,2-d][1,3]dioxin-6-yl ester