Asymmetric Deoxygenative Difunctionalization of 1,2-Dicarbonyl Compounds Enabled by Phosphinite and Chiral Salen-Molybdenum Catalyst Synergy.

The 2-aryl benzofuran-3-ones serve as pivotal scaffolds in natural products and bioactive molecules, yet their synthesis and subsequent asymmetric functionalization are hindered by multi-step protocols and the lability of their derivatives lacking electron-rich substituents on the aromatic ring of benzofuran-3-one core. Herein, we report a phosphinite-mediated, Mo-catalyzed intermolecular asymmetric deoxygenative coupling reaction between 1,2-dicarbonyl compounds and 3-(methoxymethyl)indoles, thus providing a series of chiral 2-aryl benzofuran-3-ones with a chiral quaternary carbon center with generally good yields and enantioselectivities. Mechanistic studies reveal that phosphinite and the Mo-complex synergistically promote the in situ generation of key intermediates, while the formally tetravalent mononuclear Mo-complex serves as the key species governing the enantioselectivity of the reaction. This work expands the application of chiral salen-Mo catalysts in asymmetric catalysis, offering an efficient route to valuable chiral benzofuranone derivatives.