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Nickel/Photoredox Catalyzed Aryl-Alkyl Cross-Coupling with Alkyl Boronic Esters as Radical Precursors
Li Gao1, Yi-Xuan Xin2, Peizhuo Lv1
1State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai, 200032, P. R. China.
Abstract:
Nickel/photoredox dual catalyzed cross-coupling of aryl halides with alkylboron compounds is one of the effective methodologies for the construction of C(sp2)-C(sp3) bonds. Although elegant results have been achieved by using alkyl trifluoroborates as alkyl radical precursors, the generation of alkyl radicals from readily available alkyl boronic esters is still limited due to their high oxidation potential. We disclosed here that activation of alkyl boronic esters by MeOLi is highly efficient for the generation of alkyl radicals under photocatalysis conditions. The reaction featured with a wide substrate scope, high functional group tolerance, and late-stage modification of bioactive substances. In addition, the method was also successfully extended to alkyl boronic acids. Experimental and computational mechanistic studies indicated that the cross-coupling likely proceeds via a Ni(I)-catalyzed pathway.
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