3,4-dimethyl-7-phenyl-6-thioxo-6,7-dihydropyrimido[4',5':4,5]thieno[2,3-c]pyridazin-8(5H)-one   、                                                                                      alkaline earth salt of/the/ methylsulfuric acid                                                                                                                                                              在
                                                                                                                                                                                 
sodium acetate                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
乙醇                                                                                  为溶剂,
                                                                                                                                                    反应 3.0h,
                                                                                                                以69%的产率得到methyl 2-((3,4-dimethyl-8-oxo-7-phenyl-7,8-dihydropyrimido[4',5':4,5]thieno[2,3-c]pyridazin-6-yl)thio)propanoate