Benzo-Fused Medium-Sized Heterocycles with a Chiral C–N Axis from Asymmetric Cycloaddition and Skeletal Rearrangement

We report an efficient palladium-catalyzed synthesis of diverse enantioenriched benzofused nine- and ten-membered heterocycles featuring a stereogenic carbon as well as an axially chiral N-aryl sulfonamide motif. Such a structural scaffold has shown significant pharmacological potential in related heterocyclic compounds. This method utilizes readily accessible aza-ortho-quinone methide precursors and vinyl carbonates in formal [5 + 4] and [6 + 4] cycloadditions with excellent diastereo- and enantioselectivity. Furthermore, the ten-membered heterocycles can undergo sequential ring-contractive rearrangements, providing systematic access to highly functionalized nine- and eight-membered heterocycles with excellent stereocontrol.