Catalytic Asymmetric Desymmetrizing [4+2] Cycloaddition/Base-Mediated Oxidative Aromatization Sequence: <i>De Novo</i> Synthesis of Isobenzofuranone-Embedded Chiral Arenes

Herein, an organocatalytic asymmetric desymmetrizing [4+2] cycloaddition/base-mediated oxidative aromatization reaction sequence has been developed between spirophthalide 2,5-cyclohexadienones and β-methyl cinnamaldehydes. The reaction proceeds through <i>in situ</i> chiral dienamine intermediate formation, and the densely functionalized spirocyclic isobenzofuranone-embedded chiral arenes were formed in high yields with excellent enantioselectivities. A 2-fold desymmetrization reaction was also performed, and the products were obtained in high enantioselectivities.