40626-61-7Relevant articles and documents
Visible light-promoted metal-free C-H activation: Diarylketone-catalyzed selective benzylic mono- and difluorination
Xia, Ji-Bao,Zhu, Chen,Chen, Chuo
, p. 17494 - 17500 (2014/01/06)
We report herein an operationally simple method for the direct conversion of benzylic C-H groups to C-F. We show that visible light can activate diarylketones to abstract a benzylic hydrogen atom selectively. Adding a fluorine radical donor yields the benzylic fluoride and regenerates the catalyst. The selective formation of mono- and difluorination products can be achieved by catalyst control. 9-Fluorenone catalyzes benzylic C-H monofluorination, while xanthone catalyzes benzylic C-H difluorination. The scope and efficiency of this new C-H fluorination method are significantly better than those of the existing methods. This is also the first report of selective C-H gem-difluorination.