A mild and regioselective Ullmann reaction of indazoles with aryliodides in water
作者:Xiao Ding、Jingtao Bai、Hailong Wang、Baowei Zhao、Jian Li、Feng Ren
DOI:10.1016/j.tet.2016.11.066
日期:2017.1
A mild and regioselective Ullmann reaction of indazoles with aryliodides has been developed as a general method for the synthesis of 1-aryl-1H-indazoles. Water was used as the solvent wherein Tween 20 (2% w/w) was added to form aqueous micelles to improve solubility of starting materials and accelerate reaction rate. This aqueous protocol allows the Ullmann reaction to proceed at a mild temperature
已经开发了吲唑与芳基碘化物的温和的区域选择性乌尔曼反应作为合成1-芳基-1 H-吲唑的一般方法。使用水作为溶剂,其中添加吐温20(2%w / w)以形成水性胶束,以改善起始原料的溶解度并加快反应速率。该水性方案允许Ullmann反应在较短的反应时间(2 h)内在温和的温度(60°C)下进行,这通常需要高温(≥100°C)和较长的持续时间(≥24h)。对于所检查的25个实例,该方案证明了广泛的底物范围,具有良好的分离得率和较高的区域选择性(N -1芳基化超过N -2芳基化)。