Expedient Synthesis of Axially and Centrally Chiral Diaryl Ethers via Cobalt-Catalyzed Photoreductive Desymmetrization

Axially chiral diaryl ethers make up a unique class of atropisomers bearing restricted rotation about the C-O bond. Methods for the expedient synthesis of axially chiral diaryl ether-based structures have been largely underdeveloped. Herein, we developed an efficient metal-catalyzed desymmetrization strategy to unveil the formation of axially and centrally dual chiral diaryl ethers in high diastereo- and enantioselectivity. The protocol leverages cobalt-catalyzed photoreductive enantioselective couplings of dialdehyde and alkyne to deliver dual stereogenicity, and the diaryl ether scaffold is equipped with useful synthetic handles including formyl, hydroxyl, and allyl groups, as has been demonstrated in the synthesis of a chiral carboxylic acid as a potential chiral ligand in asymmetric catalysis.