Copper-Catalyzed Enantioselective Reduction of Biaryl Dialdehydes via Bora-Brook Rearrangement

The first enantioselective Bora-Brook rearrangement reaction catalyzed by a Cu/SOP system was established. In this protocol, the synthesis of axially chiral monoaldehydes has been achieved by the desymmetric reduction of prochiral dialdehydes. This reaction proceeds smoothly under mild conditions, affording the products in high yields (up to 91%) with excellent enantioselectivities (up to 96:4 er) while exhibiting broad functional group compatibility. The synthetic utility of this approach is further demonstrated through diverse transformations of the products.