Asymmetric Three-Component Reaction to Assemble the Acyclic All-Carbon Quaternary Stereocenter via Visible Light and Phosphoric Acid Catalysis

Chiral acyclic all-carbon quaternary stereocenters are widely present in natural products and pharmaceuticals. However, their introduction remains a challenging topic in the synthetic research community. Here, we report an efficient metal-free method for the construction of acyclic all-carbon quaternary chiral centers sited at the α-position of an aldehyde or ketone moiety. This is achieved via a well-designed reaction cascade involving arylalkynes, benzoquinones, and electron-rich (hetero)arenes and the use of visible light and phosphoric acid catalysis. Notably, the asymmetric catalytic visible-light-induced Paternò–Büchi cycloaddition/electrocyclic ring-opening/α-selective arylation of α,β-unsaturated carbonyl compound cascades is achieved. Moreover, the reaction works well for a broad range of these three components (>70 examples). Furthermore, the rich chemistry embedded in the products provides a variety of synthetically useful building blocks that are otherwise difficult to access. Lastly, the origin of enantioselectivity was investigated by density functional theory, revealing that CH/π interactions play a crucial role in the stereocontrol of the reaction.