A general and practical method for the direct C–H amination of 2H-indazoles with a series of amines including aliphatic primary amines, secondary amines, azoles, and sulfoximines via organophotoredox-catalyzed oxidative coupling has been disclosed at room temperature under ambient air conditions. Additionally, this protocol is used for free aminated 2H-indazole synthesis. A mechanistic study revealed
CuO nanoparticle catalysed synthesis of 2H-indazoles under ligand free conditions
作者:Nilufa Khatun、Anupal Gogoi、Pallabita Basu、Prasenjit Das、Bhisma K. Patel
DOI:10.1039/c3ra45298k
日期:——
A CuO nano catalysed one-pot synthesis of 2H-indazoles has been devised from easily accessible starting materials viz. 2-bromobenzaldehydes, primary amines and sodium azide under ligand free conditions. The nano CuO catalyst played an important role during the formation of the intermolecular C–N bond followed by the intramolecular N–N bond, providing 2H-indazoles. This method has a broad substrate scope with a high tolerance of a variety of functional groups. The catalyst can be recycled up to three times, however with slight decreases in the yields each time.
maleimides with 2-arylindazoles via C-H activation have been demonstrated. The reaction affords 3-(2-(2H-indazol-2-yl)phenyl)succinimide and 3-(2-(2H-indazol-2-yl)phenyl)maleimide derivatives in high yields with wide functional group tolerance. A mechanistic study was performed to depict C-H bond cleavage that might be involved in the turnover limiting step.
A visible-light-promoted regioselective C(sp2)–H/C(sp3)–H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalyticamount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature underaerobicconditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields
An environmentally friendly method of electrochemical mediated regioselectiveC-3 trifluoromethylation of 2H-indazole by employing CF3SO2Na as the CF3 source was described. This reaction tolerated various functional groups and provided CH trifluoromethylated products in moderate to good yields under transitionmetal-free and oxidant-free reaction conditions. Mechanism experiments showed that a radical
描述了一种以 CF 3 SO 2 Na 作为 CF 3源的电化学介导的 2H-吲唑区域选择性 C-3 三氟甲基化的环境友好方法。该反应耐受各种官能团,并在无过渡金属和无氧化剂的反应条件下以中等至良好的产率提供 C H 三氟甲基化产物。机理实验表明,这种转变可能涉及一个激进的过程。