2,4-dichloro-8-(3,4-difluorophenyl)-7,8-dihydro-5H-pyrano[4,3-d]pyrimidine   、                                                                                      
乙胺                                                                                                                                                                                                                                                                                                          以to give 2-chloro-8-(3,4-difluorophenyl)-N-ethyl-7,8-dihydro-5H-pyrano[4,3-d]pyrimidin-4-amine (Preparation Ya)的产率得到2-chloro-8-(3,4-difluorophenyl)-N-ethyl-7,8-dihydro-5H-pyrano[4,3-d]pyrimidin-4-amine