Enantioselective Allylation of Oxocarbenium Ions Catalyzed by Bi(OAc)3/Chiral Phosphoric Acid

Phthalides as the crucial core skeletons are found extensively in natural products and biological active molecules. Herein we disclose an asymmetric allylation of 3-hydroxyisobenzofuran-1(3H)-ones with boron allylation reagents to construct chiral phthalide derivatives. The simple Bi(OAc)3/chiral phosphoric acid catalytic system proves to be efficient in this method, delivering the desired chiral 3-allylisobenzofuran-1(3H)-ones in good yields (up to 99%) and high enantioselectivities (up to 99.5:0.5 e.r.) under mild conditions. The large-scale reaction and diverse transformations of products to various scaffolds with potential biological activities render it more attractive. Moreover, the mechanism was preliminarily explored by control reactions, mass spectrometry, deuterium experiment, and DFT calculations.