Pd-Catalyzed β-H Elimination of Alkenyl Thianthrenium Salts for the Synthesis of Disubstituted Allenes

Strategies for the direct conversion of unactivated alkenes into allenes with the preservation of the carbon skeleton remain a significant synthetic challenge. Herein, we report a palladium-catalyzed synthesis of disubstituted allenes from alkenyl thianthrenium salts, which are readily accessible via the site-selective thianthrenation of alkenes. This protocol features mild reaction conditions, enabling the facile construction of acyclic and macrocyclic allenes that are difficult to access by other means. Furthermore, a preliminary enantioselective variant enabled by a chiral Xu-Phos ligand is described, providing access to axially chiral allenes with promising stereocontrol.