N4-isobutyryl-1-{(2R,3R,4R,5R)-4-benzoyloxymethyl-5-(2-hydroxyethyl)-3-[(m-trifluoromethyl)benzoyloxy]tetrahydrofuran-2-yl}cytosine 以50%的产率得到3-Trifluoromethyl-benzoic acid (2R,3R,4R,5R)-2-(4-amino-2-oxo-2H-pyrimidin-1-yl)-4-benzoyloxymethyl-5-(2-hydroxy-ethyl)-tetrahydro-furan-3-yl ester