5-[[(1R,2S,3R,4R)-2,3-(isopropylidenedioxy)-4-[[(tert-butyldimethylsilyl)oxy]methyl]cyclopentyl]aminomethyleneamino]-1-[5-O-(monomethoxytrityl)-2,3-O-(isopropylidene)-β-D-ribofuranosyl]imidazole-4-(N-2,4-dinitrophenyl)carboxamide