Palladium-Catalyzed Ring Opening of Vinyl Oxetanes Enables Asymmetric Dearomative [6 + 2] Cycloaddition of 3-Nitroindoles to Access Indoline-Fused Oxa-Eight-Membered Rings

We present a catalyst system consisting of a chiral (R)-xyl-BINAP ligand and PdCl₂, which enables the ring opening of vinyl oxetanes to drive asymmetric dearomatization of 3-nitroindoles for the enantioselective [6 + 2] cycloaddition, leading to the construction of indoline-fused oxa-eight-membered rings in good yields with high to excellent stereoselectivities (up to 96% yield, >95:5 dr, and 98% ee). This work represents the first example of asymmetric dearomatization of electron-deficient nitroindoles triggered by oxa-π-allylpalladium 1,6-dipoles.