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(sp 3 )À 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 CÀ S axis. All three stereoisomers were addressable with enantioand diastereodivergence and a stereoselectivity of up to (À sc): (+ sc) : (ap) = 94 : 6 : < 1.

o-Quinodimethanes have remarkable utility as reactive intermediates in Diels-Alder reactions, enabling significantly accelerated routes to complex polycyclic compounds. The discovery of different discrete precursors to thermally generate o-quinodimethanes thereby greatly augmented their availability and versatility. However, due to the required high temperatures and the immense reactivity of o-quinodimethanes, stereoselectivity to afford isomerically defined products still constitutes a critical challenge. Herein, we describe the accessibility of atropisomeric o-quinodimethanes, the enantioselective synthesis of their precursors, their remarkable configurational stability and the stereospecific transformation by the benzannulation of dienophiles. A catalyst-stereocontrolled [2+2+2] cycloaddition, the generation of o-quinodimethane atropisomers and ensuing stereospecific Diels-Alder reactions enabled enantioselectivities through these transient intermediates with of up to 96 : 4 e.r.

No abstract

o-Quinodimethanes have remarkable utility as reactive intermediates in Diels-Alder reactions, enabling significantly accelerated routes to complex polycyclic compounds. The discovery of different discrete precursors to thermally generate o-quinodimethanes thereby greatly augmented their availability and versatility. However, due to the required high temperatures and the immense reactivity of o-quinodimethanes, stereoselectivity to afford isomerically defined products still constitutes a critical challenge. Herein, we describe the accessibility of atropisomeric o-quinodimethanes, the enantioselective synthesis of their precursors, their remarkable configurational stability and the stereospecific transformation by the benzannulation of dienophiles. A catalyst-stereocontrolled [2+2+2] cycloaddition, the generation of o-quinodimethane atropisomers and ensuing stereospecific Diels-Alder reactions enabled enantioselectivities through these transient intermediates with of up to 96 : 4 e.r.

Katalysatorkontrolle über Stereogenität höherer Ordnung vergrößert den zugänglichen stereochemischen Raum erheblich, aber Methoden zur stereoselektiven Synthese dreifach stereogener Einheiten wurden bisher nicht beschrieben. In diesem Artikel berichten wir über die stereokontrollierte Synthese von dreifach stereogenen Triptycylsulfonen, deren Atropisomerie aus einer C(sp3)−S‐Bindung resultiert. Die katalysatorkontrollierte Oxidation eines stereodynamischen Thioethers in Gegenwart einer chiralen Phosphorsäure erlaubte dabei den selektiven Zugang zu enantiomerenangereicherten Triptycylsulfoxiden. Deren anschließende enantiospezifische und diastereoselektive katalytische Oxidation zu einem dreifach stereogenen Sulfon ermöglichte es so, die stereogene C−S‐Achse zu kontrollieren. Alle drei Stereoisomere wurden mit Enantio‐ und Diastereodivergenz und einer Stereoselektivität von bis zu (−sc) : (+sc) : (ap)=94 : 6 : <1 erhalten.