Asymmetric Formal\n[5 + 2] Annulation of 3‑Hydroxyquinolinones\nand Vinylethylene Carbonates through Pd/Cu Tandem Catalysis

The\nasymmetric [5 + 2] cycloaddition of VECs remains to be comparatively\nrare. Herein, we reported an enantioselective formal [5 + 2] annulation\nof 3-hydroxyquinolinones and vinylethylene carbonates (VECs) through\nPd- and Cu-catalyzed tandem allylation/asymmetric [1,3]-rearrangement/hemiketalization\nsequences. The strategy exhibits good substrate tolerance, affording\na wide range of tricyclic quinolinones bearing two adjacent quaternary\nstereocenters in moderate to good yields with excellent enantioselectivities.