Visible-light photoredox catalyzed cyclization of aryl alkynoates for the synthesis of trifluoromethylated coumarins
作者:Mei-jie Bu、Guo-ping Lu、Chun Cai
DOI:10.1016/j.catcom.2018.06.009
日期:2018.8
for the synthesis of coumarin derivatives via visible-lightphotoredoxcatalysis has been developed using fac-Ir(ppy)3 as the photocatalyst under mild conditions. Trifluoromethanesulfonyl chloride is utilized as the trifluoromethylation reagent, which is cheap and readily available. Aryl alkynoates are trifluoromethylated, then undergo a radical cyclization and a cascade ester migration to generate target
catalysis strategy for the direct trifluoromethylation of coumarins with inexpensive sodium triflinate (Langlois reagent, CF3SO2Na) as the CF3 source under xenon lamp irradiation is described. The reaction proceeds under ambient conditions and affords the corresponding products in moderate yields. The acetone can be used as low-cost radical initiator to generate CF3 radicals from sodium triflinate efficiently
描述了一种简单,无金属和氧化剂的光催化策略,用于在氙气灯照射下,使用廉价的三氟甲酸钠(Langlois试剂,CF 3 SO 2 Na)作为CF 3源直接对香豆素进行三氟甲基化。反应在环境条件下进行,并以中等收率得到相应的产物。丙酮可用作低成本的自由基引发剂,可从三氟甲磺酸钠高效生成CF 3自由基。
Photoredox-Catalyzed Cascade Radical Cyclization of Ester Arylpropiolates with CF<sub>3</sub>SO<sub>2</sub>Cl To Construct 3-Trifluoromethyl Coumarin Derivatives
We report a highly efficient method to construct 3-trifluoromethyl coumarins using CF3SO2Cl as the trifluoromethyl radical source with ester 3-arylpropiolates. The reaction incorporated a cascade cyclization/dearomatization/ester migration/oxidization/rearomatization process to afford various 3-trifluoromethyl coumarins under visible light irradiation in good to excellent yields.
我们报告了一种高效的方法来构建3-三氟甲基香豆素,使用CF 3 SO 2 Cl作为带有3-芳基丙酸酯的三氟甲基自由基源。该反应结合了级联环化/脱芳香化/酯迁移/氧化/重芳香化过程,以可见光照射以良好至优异的产率提供了各种3-三氟甲基香豆素。
A mild and fast continuous-flow trifluoromethylation of coumarins with the CF<sub>3</sub> radical derived from CF<sub>3</sub>SO<sub>2</sub>Na and TBHP
Leaving Group Assisted Strategy for Photoinduced Fluoroalkylations Using <i>N</i>
-Hydroxybenzimidoyl Chloride Esters
作者:Weigang Zhang、Zhenlei Zou、Yuanheng Wang、Yi Wang、Yong Liang、Zhengguang Wu、Youxuan Zheng、Yi Pan
DOI:10.1002/anie.201812192
日期:2019.1.8
(RAEs) as alkylradical precursors have been extensively developed for C−C bond formations. However, the analogous transformations of fluoroalkyl radicalsfrom the corresponding acid or ester precursors remain challenging because of the high oxidation potential of the fluoroalkyl carboxylate anions. The newly developed N‐hydroxybenzimidoylchloride (NHBC) ester provides a general leavinggroup assisted