Pd-Catalyzed Dearomatization of Anthranils with Vinylcyclopropanes via [4+3] Cyclization Reaction

Dearomatization of anthranils with vinylcyclopropanes (VCPs) via Pd-catalyzed [4+3] cyclization reaction has been realized. In the presence of a catalytic amount of borane as an activator, bridged cyclic products were obtained in good to excellent yields with excellent stereoselectivities. By introducing a chiral PHOX ligand (L5), asymmetric dearomatization reactions of anthranils with vinylcyclopropanes proceeded with excellent enantioselectivity. Borane plays a key role for the reactivity, likely due to the formation of a borane-anthranil complex which has been confirmed by the NMR experiments.