[(2R,3R,4R,5R)-3,4-Dihydroxy-2-(4-hydroxy-2-oxo-2H-pyrimidin-1-yl)-5-trityloxymethyl-tetrahydro-furan-3-yl]-phosphonic acid diethyl ester                                                                                                                                                              在
                                                                                                                                                                                 
三氟甲烷磺酰氯   、                                                                                                  
4-吡咯烷基吡啶                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
二氯甲烷                                                                                  为溶剂,
                                                                                                                                                    反应 1.0h,
                                                                                                                以79%的产率得到[(1R,2R,4R,5S)-2-(4-Hydroxy-2-oxo-2H-pyrimidin-1-yl)-4-trityloxymethyl-3,6-dioxa-bicyclo[3.1.0]hex-1-yl]-phosphonic acid diethyl ester