Photoredox‐Catalyst‐Enabled <i>para</i>‐Selective Trifluoromethylation of <i>tert</i>‐Butyl Arylcarbamates
Yaqiqi Jiang, Bao Li, Nana Ma, Sai Shu, Yujie Chen, Shan Yang, Zhibin Huang, Daqing Shi, Yingsheng Zhao
Abstract
The direct incorporation of a trifluoromethyl group on an aromatic ring using a radical pathway has been extensively investigated. However, the direct highly para-selective C-H trifluoromethylation of a class of arenes has not been achieved. In this study, we report a light-promoted 4,5-dichlorofluorescein (DCFS)-enabled para-selective C-H trifluoromethylation of arylcarbamates using Langlois reagent. The preliminary mechanistic study revealed that the activated organic photocatalyst coordinated with the arylcarbamate led to para-selective C-H trifluoromethylation. Ten-gram scale reaction performs well highlighting the synthetic importance of this new protocol.