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.