Synthesis of Axially Chiral Allenes by Pd-Catalyzed Thianthrene-Mediated Functionalization of Alkynes with Arenes

A strategy based on sequential "C-H thianthrenation/Pd-catalyzed asymmetric Heck reaction" was designed to synthesize trisubstituted chiral allenes from nonprefunctionalized arenes directly. This innovative approach successfully addressed challenging cyclic and acyclic systems while enabling the late-stage modification of complex small molecules. The methodology exhibited remarkable robustness through its successful implementation in a gram-scale reaction and the recycling of thianthrene. Density functional theory computation results reveal that the enantioselective step follows a base-accelerated β-H elimination mechanism.