Studies On The Synthesis Of Indazoles

Heterocyclic compounds is an important part of organic chemistry. About one third ofall the organic compounds are heterocyclic compounds. The indazole subunit is afrequently found motif in drug substances with important biological activities such asanti-HIV, anti-tumor and anti-inflammatory. Despite the importance of indazoles inpharmaceutical development, the invention of efficient and general methodologies forsynthesis of indazoles has met with limited success. In this paper, the synthetic routes of2-aryl-2H-indazoles and 1-aryl-1H-indazoles were designed, studied and discussed. As aresult, we found that 2-aryl-2H-indazoles was developed by copper(I)-catalyzedintramolecular amination reaction under the condition of [CuI/Cs₂CO₃/1,4-dioxane/105℃]starting from N'-aryl-N'-(o-bromobenzyl)- acetylhydrazines. And 1-ary-1H-indazoleswere obstained by using commercially available copper(I) iodide as an effective catalystunder the condition of [CuI/KOH/1,4-dioxane/105℃] starting from various arylhydrazones.The method was applied to a wide scope of substrates and afforded indazole products inhigh yields.