Catalytic Asymmetric\nDesymmetrizing [4+2] Cycloaddition/Base-Mediated\nOxidative Aromatization Sequence: <i>De Novo</i> Synthesis\nof Isobenzofuranone-Embedded Chiral Arenes

Herein, an organocatalytic asymmetric desymmetrizing\n[4+2] cycloaddition/base-mediated\noxidative aromatization reaction sequence has been developed between\nspirophthalide 2,5-cyclohexadienones and β-methyl cinnamaldehydes.\nThe reaction proceeds through <i>in situ</i> chiral dienamine\nintermediate formation, and the densely functionalized spirocyclic\nisobenzofuranone-embedded chiral arenes were formed in high yields\nwith excellent enantioselectivities. A 2-fold desymmetrization reaction\nwas also performed, and the products were obtained in high enantioselectivities.