Synthesis of 3-Amino-substituted N-Alkylindazoles via Palladium(II)-catalyzed Intramolecular N-Arylation of Tosylhydrazines

Abstract An efficient synthesis of 3-amino-substituted N-alkyl indazoles is described. Reaction of readily available o-halo aryl hydrazines with palladium(II) acetate and cupper(I) iodide in the presence of a base afforded the corresponding 3-substituted N-tosylindazoles in excellent yields. These products were further functionalized after detosylation with Na–Hg, followed by alkylation to afford 3-amino-substituted N-alkylindazoles.