The base-free O-difluoromethylation of 1,3-diones with difluorocarbene generated from difluoromethylene phosphobetaine (Ph3P+CF2CO2−) is described. The convenient reactions proceeded smoothly to give difluoromethyl enol ethers in moderate to good yields.
游离碱- O-的二氟亚甲基从生成磷酸酯1,3-二酮与二氟卡宾二氟甲基(PH 3 P + CF 2 CO 2 - )进行说明。方便的反应顺利进行,以中等至良好的产率得到二氟甲基烯醇醚。
Selective <i>O</i>-Difluoromethylation of 1,3-Diones by Bromodifluoromethylating Reagents
The regioselective Odifluoromethylation of 1,3-diones was achieved via in situ generation of difluorocarbene from bromodifluoromethylating reagents in the presence of an organic base. A wide variety of difluormethyl enol ethers were obtained in good to excellent yields. The reaction mechanism is discussed based on ab initio calculations (kcal/mol).
Selective O-difluoromethylation of 1,3-diones using S-(difluoromethyl) sulfonium salt
作者:Guo-Kai Liu、Xin Li、Wen-Bing Qin、Wei-Feng Lin、Li-Ting Lin、Jia-Yi Chen、Jian-Jian Liu
DOI:10.1016/j.cclet.2019.03.036
日期:2019.8
A facile and highly efficient approach for selective O-difluoromethylation of 1,3-diones by recently developed bench-stable S-(difluoromethyl)sulfonium salt was described. And a broad range of difluoromthyl enol ethers were readily accessed in good to excellent yields under mild reaction conditions. Mechanistic studies revealed that the O-difluoromethylation reaction proceeds mainly via a difluorocarbene pathway. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.