8-(4-(trifluoromethyl)phenyl)-7,8-dihydropyrano[3,4-e][1,3]oxazine-2,4(3H,5H)-dione   、                                                                                      
ammonium hydroxide                                                                                                                                                                                                                                                                                                          以to give 8-(4-(trifluoromethyl)phenyl)-7,8-dihydro-1H-pyrano[4,3-d]pyrimidine-2,4(3H,5H)-dione (Intermediate Z(4))的产率得到8-(4-(trifluoromethyl)phenyl)-7,8-dihydro-1H-pyrano[4,3-d]pyrimidine-2,4(3H,5H)-dione