methyl hexahydro-1,3-dioxo-1H-1,2,4-triazolo[1,2-a]-pyridazine-5-carboxylate 、
1-溴-2-氯乙烷 以gave methyl 2-(2-chloroethyl)-2,3,5,6,7,8-hexahydro-1,3-dioxo-1H-1,2,4-triazolo[1,2-a]pyridazine-5-carboxylate of melting point 94°-95° C.的产率得到methyl 2-(2-chloroethyl)-2,3,5,6,7,8-hexahydro-1,3-dioxo-1H-1,2,4-triazolo[1,2-a]-pyridazine-5-carboxylate