Michael Reaction Inspired Atroposelective Construction of Axially Chiral Biaryls.

The first copper-catalyzed atroposelective Michael-type addition between azonaphthalenes and arylboronic acids for the construction of biaryl atropisomers was established using a novel BINOL-derived phosphoramidite as a chiral ligand. A broad range of atropisomeric biaryls were obtained with good efficiency, and the practicality of this approach was verified by versatile transformations toward axially chiral ligands, catalysts, and other functional atropisomers. This set of catalytic systems successfully inhibited the routine 1,2-addition and promoted the formation of an aryl-aryl chiral axis. Meanwhile, this strategy bypassed the use of an oxidant as well as the harsh conditions normally necessary for transition-metal-mediated arene C-H coupling with arylboronic acids as an arylation counterpart, offering a straightforward alternative to access optically active biaryls.