A Versatile and Efficient Synthesis of Substituted 1H-Indazoles

Abstract

A facile synthesis of substituted 1H-indazole 4 from aryl mesylate 3 is described. The reaction, which proceeds through the intermediate hydrazone, was general with regard to the substituents on the arene and was applicable to several hydrazines. It was also discovered that with p-methoxyphenylhydrazine, the indazole formation was more rapid than the competitive Fischer indole synthesis.