title: Synthesis of indazoles and azaindazoles by intramolecular aerobic oxidative C-N coupling under transition-metal-free conditions.
abstract: A transition-metal-free oxidative C-N coupling method has been developed for the synthesis of 1H-azaindazoles and 1H-indazoles from easily accessible hydrazones. The procedure uses TEMPO, a basic additive, and dioxygen gas as the terminal oxidant. This reaction demonstrates better reactivity, functional group tolerance, and broader scope than comparable metal catalyzed reactions.
authors.affiliation: MOE Key Laboratory of Protein Sciences, Department of Pharmacology and Pharmaceutical Sciences, School of Medicine and School of Life Sciences, Tsinghua University, Beijing 100084 (China).
authors.forename: Jiantao
authors.initials: J
authors.lastname: Hu
authors.forename: Huacheng
authors.initials: H
authors.lastname: Xu
authors.forename: Pengju
authors.initials: P
authors.lastname: Nie
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Xie
authors.forename: Zongxiu
authors.initials: Z
authors.lastname: Nie
authors.forename: Yu
authors.initials: Y
authors.lastname: Rao
mesh_terms: D002384:Catalysis; D007191:Indazoles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D058451:Oxidative Coupling
chemical_list: D007191:Indazoles; D008670:Metals
keywords: aerobic oxidative CN coupling; azoindazole; heterocycles; indazole; metal-free condition