Diastereoselective Access to Seven-Membered Benzosultams via Palladium-Catalyzed Ring-Opening [3+2]-Annulation

A palladium-catalyzedring-opening [3 + 2]-annulation of spirovinylcyclopropanyloxindoles with seven-membered cyclic N-sulfonylimineshas been developed. A wide range of seven-membered benzosultams featuringboth a quaternary center and axially chiral biaryl scaffolds havebeen afforded in an average yield of 87% with moderate to excellentdiastereoselectivities. The enantioenriched benzosultams were alsoaccessed successfully in good yields with excellent atropoenantioselectivitiesenabled by the Pd-2(dba)(3)/(S,S,S)-SKP ligand. The practicalutility of this protocol was further demonstrated by the gram-scalereaction and diversified synthetic transformations of the desiredseven-membered benzosultam.