title: Selective synthesis of indazoles and indoles via triazene-alkyne cyclization switched by different metals.
abstract: We described two orthogonal heterocycle syntheses, where an arene bearing both an alkyne and a triazene functionality underwent two distinct cyclization pathways mediated by different transition metals. Starting from the same substrates, a synthesis of 2H-indazole was accomplished by a Cu(II) salt promoted oxidative cyclization, while 2-substituted indoles could be accessed via a Ag(I) salt mediated N-N bond cleavage. This method represents the first synthesis of indoles from alkynyl triazenes. Computational analysis was performed for both reaction pathways, supporting a Lewis acid role for Cu and a π-acid catalysis for Ag.
authors.affiliation: Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University, Shenzhen Graduate School, Shenzhen, China. huangyong@pkusz.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Fang
authors.forename: Chengming
authors.initials: C
authors.lastname: Wang
authors.forename: Shengqin
authors.initials: S
authors.lastname: Su
authors.forename: Haizhu
authors.initials: H
authors.lastname: Yu
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D007191:Indazoles / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D012834:Silver / Q000737:chemistry*; D014226:Triazenes / Q000737:chemistry*
chemical_list: D000480:Alkynes; D007191:Indazoles; D007211:Indoles; D014226:Triazenes; D012834:Silver; D003300:Copper