A general and practical regioselective approach for the C–H amination of 2H-indazoles under transition-metal-free conditions was developed. A series of substrates were tested showing eminent functional group tolerance and affording the C–N functionalization products in good to excellent yields. Mechanism studies revealed that a radical process was involved in this transformation.
direct synthesis of 3-substituted-2H-indazole derivatives was developed in the presence of AgNO3/Na2S2O8 under mild reaction conditions. The reaction affords a series of 1,3-dicarbonyl-2H-indazoles products with yields of up to 82%. The mechanism of the strategy suggests that the reaction proceeds through a radical pathway. Moreover, this strategy provides a new protocol for the synthesis of functionalized
在温和的反应条件下,在 AgNO 3 /Na 2 S 2 O 8存在下,开发了一种直接合成 3-取代-2 H-吲唑衍生物的便捷策略。该反应提供了一系列 1,3-二羰基-2 H-吲唑产物,产率高达 82%。该策略的机制表明反应通过自由基途径进行。此外,该策略为功能化 2 H-吲唑的合成提供了新的方案。
A Facile One-Step Synthesis of 2-Arylindazoles via Reductive Cyclization of<i>N</i>-(2-nitroarylidene)amines
作者:Wei Lin、Minghua Hu、Xian Feng、Chengpao Cao、Zhibin Huang、Daqing Shi
DOI:10.1002/jhet.2221
日期:2015.7
A mild and efficient synthesis of 2‐arylindazole derivatives via the reductivecyclization of nitro‐aryl substrates mediated by a low‐valent titanium reagent (TiCl4/Sm/Et3N) has been developed. The attractive features of the current method include an N–N bond formation and the selective reduction of the C = N bond and nitro group, both of which were easily achieved in one‐pot by controlling the pH
通过低价钛试剂(TiCl 4 / Sm / Et 3 N)介导的硝基芳基底物的还原环化,可以温和有效地合成2-芳基吲唑衍生物。当前方法的吸引人的特征包括N–N键的形成以及C = N键和硝基的选择性还原,通过控制反应混合物的pH值,很容易在一个锅中完成这两个操作。
Electrochemically mediated trifluoromethylation of 2H-indazole derivatives using CF3SO2Na
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。
An efficient synthesis of 2H-indazoles via reductive cyclization of 2-nitrobenzylamines induced by low-valent titanium reagent
作者:Fang Sun、Xian Feng、Xuan Zhao、Zhi-Bin Huang、Da-Qing Shi
DOI:10.1016/j.tet.2012.03.043
日期:2012.5
An efficient and improved synthesis of 2H-indazoles via reductive cyclization of 2-nitrobenzylamines induced by low-valenttitaniumreagent (TiCl4/Zn) is described. In this reaction triethylamine (TEA) was used to control the pH value. This method has the advantages of easily accessible starting materials, convenient manipulation, higher yield, shorter reaction time, and wider substrate scope.