Rhodium-Catalyzed Si–H Bond Insertion Reactions Using Functionalized Alkynes as Carbene Precursors
journal contributionposted on 03.05.2019 by Ming-Yao Huang, Ji-Min Yang, Yu-Tao Zhao, Shou-Fei Zhu
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Enantioselective transition-metal-catalyzed carbene insertion into Si–H bonds is a promising method for preparing chiral organosilicons; however, all the carbene precursors used to date in this reaction have been diazo compounds, which significantly limits the structural diversity of the resulting chiral organosilicons. Herein, we report a protocol for rhodium-catalyzed asymmetric Si–H bond insertion reactions that use functionalized alkynes as carbene precursors. With chiral dirhodium tetracarboxylates as catalysts, the reactions of carbonyl-ene-ynes and silanes smoothly gave chiral organosilanes in high yields (up to 98%) with excellent enantioselectivity (up to 98% ee). Kinetic studies suggest that insertion of the in situ-generated rhodium carbenes into the Si–H bonds of the silanes is probably the rate-determining step. This work represents the first enantioselective Si–H bond insertion reaction using alkynes as carbene precursors and opens the door for preparing chiral organosilicons with unprecedented structural diversity from readily available alkynes.