Quaternary Chiral\nPhthalides Enabled by Dirhodium(II)/Phosphine\nCatalyzed Asymmetric Carbonyl Addition Cascade

The catalytic asymmetric synthesis of chiral phthalides\nhas garnered\nconsiderable interest. However, the construction of phthalides with\na chiral quaternary carbon stereocenter still remains challenging.\nIn this study, we developed a new strategy toward catalytic asymmetric\nsynthesis of chiral 3,3-disubstituted phthalides via a dirhodium(II)/phosphine-catalyzed\ncarbonyl addition cascade, yielding phthalides with up to 97% ee values.\nThe reaction proceeded through dirhodium(II)/phosphine-catalyzed asymmetric\ncarbonyl addition of arylboronic acids to isoquinoline-1,3,4(2<i>H</i>)-triones, followed by base-mediated ring contraction.