Palladium-Catalyzed Enantioselective Arylation of Aryl Sulfenate Anions: A Combined Experimental and Computational Study

A novel approach to produce chiral diaryl sulfoxides from aryl benzyl sulfoxides and aryl bromides via an enantioselective arylation of aryl sulfenate anions is reported. A (JosiPhos)­Pd-based catalyst successfully promotes the asymmetric arylation reaction with good functional group compatibility. A wide range of enantioenriched diaryl, aryl heteroaryl, and even diheteroaryl sulfoxides were generated. Many of the sulfoxides prepared herein would be difficult to prepare via classic enantioselective oxidation of sulfides, including Ph­(Ph-<i>d</i>₅)­SO (90% ee, 95% yield). A DFT-based computational study suggested that chiral induction originates from two primary factors: (i) both a kinetic and a thermodynamic preference for oxidative addition that places the bromide trans to the JosiPhos-diarylphosphine moiety and (ii) Curtin–Hammett-type control over the interconversion between <i>O</i>- and <i>S</i>-bound isomers of palladium sulfenate species following rapid interconversion between <i>re</i>- and <i>si</i>-bound transmetalation products, <i>re</i>/<i>si</i>-Pd–<i>O</i>SPh (<i>re</i>/<i>si</i>-PdO-<i>trans</i>)