Formylation of N-arylpyrazole containing active amino group using Vilsmeier–Hacck reaction

Two species of N-arylpyrazoles containing active amino group were synthesized. And formylations of N-arylpyazoles containing amino in different position of pyrazole rings using Vilsmeier–Hacck reaction gave a series of useful pyrazole intermediates. The important features of this protocol were cheap materials, easy process, mild reaction conditions and good yield of products.