(1R,3R,4R,5R,7S)-3-(N2-acetylguanin-9-yl)-1-(4,4'-dimethoxytrityoxy)methyl-7-hydroxy-5-methyl-2-oxabicyclo[2.2.1]heptane   、                                                                                      
2-氰乙基N,N-二异丙基氯亚磷酰胺                                                                                                                                                              在
                                                                                                                                                                                 
N,N-二异丙基乙胺                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
二氯甲烷                                                                                  为溶剂,
                                                                                                                                                                                        以77%的产率得到(1R,3R,4R,5R,7S)-3-(N2-acetylguanin-9-yl)-7-(2-cyanoethoxydiisopropylaminophosphinoxy)-1-(4,4'-dimethoxytrityloxy)methyl-5-methyl-2-oxabicyclo[2.2.1]heptane