Palladium-Catalyzed Dynamic Kinetic Asymmetric Transformation of Racemic Biaryls: Axial-to-Central Chirality Transfer

The
first dynamic kinetic asymmetric transformation of racemic biaryl
substrates on the basis of axial-to-central chirality transfer has
been realized. Chiral Pd-NHC complexes were found to catalyze the
dynamic kinetic asymmetric spiroannulation of 4-(2-bromoaryl)-naphthalen-1-ols
(or 2′-bromo-[1,1′-biphenyl]-4-ols) with internal alkynes,
affording a series of enantioenriched spirocyclic products bearing
an all-carbon quaternary stereocenter in good yields (up to 95%) with
excellent enantioselectivities (up to 97% ee).