First Atropo‐Enantioselective Ring Opening of Achiral Biaryls Containing Lactone Bridges with Chiral Hydride‐Transfer Reagents Derived from Borane

Abstract

An impressive example of the directed “twisting” of bridged, configuratively labile biaryls with chiral H-nucleophiles is seen in the atropo-enantioselective, ring-opening reduction of lactone 1 to alcohol 2 with borane THF in the presence of the chiral oxazaborolidine 3. After one recrystallization 2 is enantiomerically pure.