(2R,3R,4R,5S,9S)-3,9-diacetoxy-4-benzyloxy-2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-1-oxaspiro[4.4]non-6-ene                                                                                                                                                              在
                                                                                                                                                                                 
potassium carbonate                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
甲醇                                                                                  为溶剂,
                                                                                                                                                    反应 0.5h,
                                                                                                                以91%的产率得到(2R,3R,4R,5R,9S)-4-benzyloxy-3,9-dihydroxy-2-(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-1-oxaspiro[4.4]non-6-ene