Highly tunable multi-borylation of gem-difluoroalkenes via copper catalysis

Multi-borylated compounds are useful starting materials for the construction of complex molecules. Although certain classes of multi-borylated compounds, such as geminal and 1,2-bis(boronates), can now be accessed selectively by several well-established methods, the synthesis of one class-those containing more than two boronate substituents-remains a great challenge. Here, copper catalytic systems were developed for the borylation of gem-difluoroalkenes with B(2)pin(2) via dual C-F bond activation to afford multi-borylate libraries-1,2-alkyldiboronates, 1,1,2-alkyltriboronates and 1,1,1,2-alkyltetraboronates-by slightly tuning the reaction conditions. The advantages of this strategy include not only avoiding the use of different methods and substrates for each type of multi-substituted alkyl boronate, but also the excellent functional group compatibility, readily accessible gem-difluorovinyl group and highly chemoselective process.