5-Chloro-N-[(1R)-2,3-dihydro-1H-inden-1-yl]-3-[5-O-[methoxy[8-methyl-2-[[[(1-methylethoxy)carbonyl]oxy]methoxy]-2-oxido-6-oxo-3,5,7-trioxa-2-phosphanon-1-yl]phosphinyl]-β-D-ribofuranosyl]-3H-1,2,3-triazolo[4,5-d]pyrimidin-7-amine