| 摘要 |
PURPOSE:To obtain the titled compound in high yield at a low cost with single step without separating reaction intermediate from the system, by using thiosemicarbazide as a raw material and reacting the material with a compound such as an alpha-acyl-alpha-haloacetic acid alkyl ester essentially in an organic solvent. CONSTITUTION:Thiosemicarbazide is made to react with a compound of formula I (R<1> and R<2> are alkyl, cycloalkyl, aryl or heterocyclic group; X is halogen, alkylsulfonyloxy or arylsulfonyloxy) (e.g. ethyl-2-chloroacetoacetate) essentially in an organic solvent (containing >=15% organic solvent, preferably an alcohol) to obtain the objective 5-aminopyrazole-4-carboxylate of formula II (A is protonic acid; n>=0) (e.g. ethyl 3-methyl-5-aminopyrazole-4-carboxylate). USE:An intermediate for photographic coupler, especially a magenta coupler. |
