Synthesis of Bridged Biaryl Atropisomers via Sequential Cu- and Pd-Catalyzed Asymmetric Ring Opening and Cyclization.

Bridged biaryl atropisomers are important units in bioactive molecules. A synthesis of lactone-bridged biaryl atropisomers was realized by a Cu-catalyzed asymmetric ring-opening/acyoxylation of cyclic diaryliodoniums, followed by a palladium-catalyzed diastereoselective cyclization. It was found that a catalytic amount of Cu(OTf)2 served as an additive to promote the palladium-catalyzed Heck cyclization.