Merging Photocatalysis with Chiral Lewis Acid Catalysis for Enantioselective Hydrosilylation/Hydrogermylation of Electron-Deficient Alkenes.

Abstract

Organosilicon compounds demonstrate widespread applications in many fields. Transition-metal-catalyzed asymmetric hydrosilylation represents one of the most common and effective methods to synthesize chiral organosilicon compounds, but it largely relies on electron-rich alkenes and structurally specific hydrosilanes. Visible light photocatalysis has emerged as a promising new platform for hydrosilylation. However, the enantiocontrol of photoinduced asymmetric hydrosilylation concerning highly reactive radical species is a great challenge. Herein, we report a synergistic catalytic strategy for enantioselective hydrosilylation of electron-deficient alkenes by merging anthraquinone as a dual-tasked photocatalyst with a chiral Lewis acid catalyst. This protocol shows broad hydrosilane scope with efficient chemo-, regio- and enantioselectivities, delivering diverse enantioenriched organosilicon compounds, which could be readily converted into a series of medicine molecules. Mechanistic studies reveal that the π-π interaction between the photocatalyst and the alkene is crucial for enantiocontrol. Additionally, enantioselective radical hydrogermylation was also achieved under the visible light photoinduced synergistic catalysis.