TIANFU-CHEM 1-Pyrrolidinecarboxylic acid, 3,4-bis(benzoyloxy)-2-[(benzoyloxy)methyl]-5-[4-(1-methylhydrazino)-5H -pyrrolo[3,2-d]pyrimidin-7-yl]-, 1,1-dimethylethyl ester, (2R,3R,4S,5S)-