乙酸酐   、                                                                                      
7-(N,N-dibutylformamidino)amino-1-(2-deoxy-5-O-(4,4'-dimethoxytrityl)-β-D-ribofuranosyl)imidazo[5',4':4,5]pyrido[2,3-d]pyrimidin-4(5H)-one                                                                                                                                                              在
                                                                                                                                                                                 
吡啶                                                                                                                                  作用下,
                                                                                                                                                                                        反应 6.0h,
                                                                                                                以62%的产率得到7-(N,N-dibutylaminomethylidene)amino-1-[2-deoxy-3-O-acetyl-5-O-(4,4'-dimethoxytrityl)-β-D-ribofuranosyl]imidazo[5',4':4,5]pyrido[2,3-d]pyrimidin-4(5H)-one