Rh 2 (II)-Catalyzed Asymmetric Si–H Insertion of α-Alkyl-Donor Carbene from Diynes: Constructing C/Si-Stereocenters by Outcompeting β-H Migration

Transition metal-catalyzed asymmetric carbene Si–H insertion provides a straightforward and powerful protocol to access chiral organosilicon compounds. However, the silanes employed are largely limited to tertiary silanes, and the Si–H insertion of secondary silanes for the formation of Si-stereocenters is still underdeveloped. Herein, we report an enantioselective Si–H insertion of secondary silanes and α-alkyl-donor dirhodium-carbene generated from the cycloisomerization of diynes. This protocol delivers diverse silyl-substituted furan-fused dihydropyridine derivatives bearing C/Si-stereocenters with high efficiency (0.5 mol % catalyst loading, up to 93% yield) and good stereoselectivity (up to 99% ee, 96:4 dr). Critically, the chemoselectivity favoring intermolecular Si–H insertion over intramolecular β-hydride migration reaches up to 20:1. Notably, this protocol is successfully extended to primary silanes. The retained Si–H bonds in the products provide access for preparing chiral tetra-substituted silicon-stereogenic compounds, and the furan moiety allows further derivatization. Mechanistic studies indicated that the concerted 3 + 2 cycloaddition process is the rate-determining step. The furyl ring adjacent to dirhodium carbene was found to be essential for high chemoselectivity, as its favorable π–π stacking interactions and reduced steric hindrance stabilize the Si–H insertion transition state while outcompeting β-hydride migration