Rhodium-Catalyzed Si-H Bond Insertion Reactions Using Functionalized Alkynes as Carbene Precursors

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.