4R-{(1S,7R,10S)-8-N-benzyl-N-(2-cyanoethyl)-3,8-diaza-9-oxa-2-oxobicyclo[5.3.0]decan-10-yl}-2,3-di-O-tert-butyldimethylsilyl-1-(uracil-1-yl)-β-D-erythrofuranose

4R-{(1R,7S,10R)-8-N-benzyl-3,8-diaza-9-oxa-2-oxobicyclo[5.3.0]decan-10-yl}-2,3-di-O-tert-butyldimethylsilyl-1-(uracil-1-yl)-β-D-erythrofuranose