Asymmetric Construction of Tertiary/Secondary Carbon–Phosphorus Bonds via Bifunctional Phosphonium Salt Catalyzed 1,6-Addition

The
carbon–phosphorus bond engenders distinctive physicochemical
properties and has significant applications in chemical science. Herein,
we disclose an efficient and practical catalytic protocol for the
asymmetric synthesis of remote C–P bonds by a synergistic strategy
of stabilizing the P-nucleophile by a chiral phosphonium salt catalyst
together with activating the extended π-system by a side group,
thus leading to a cascaded 1,6-addition/aromatization reaction. This
protocol provides straightforward and expedient access to an array
of both tertiary and secondary C–P stereocentralized molecules
in high yield with exciting enantioselectivities (up to >99% ee).
Moreover, systematic mechanistic studies, including thorough DFT calculations
and control experiments, provide insights into the mechanism.