Catalyst Control over Threefold Stereogenicity: Selective Synthesis of Atropisomeric Sulfones with Stereogenic C-S Axes.

Abstract

Catalyst control over higher-order stereogenicity addresses significantly extended stereochemical space, but selective methods to govern threefold stereogenic units remained elusive. Herein, we report the stereoselective synthesis of threefold stereogenic triptycyl sulfones with atropisomerism arising from a C(sp3 )-S bond. An oxidation of a stereodynamic thioether controlled by a chiral phosphoric acid catalyst allowed selective access to enantioenriched triptycyl sulfoxides. The ensuing enantiospecific and diastereoselective catalytic oxidation to a threefold stereogenic sulfone provided overall control over the stereogenic C-S axis. All three stereoisomers were addressable with enantio- and diastereodivergence and a stereoselectivity of up to (-sc): (+sc) : (ap)=94 : 6 :<1.