Enantioselective Synthesis of Isoflavanones and Pterocarpans through a RuII‐Catalyzed ATH‐DKR of Isoflavones

Abstract Noyori‐Ikariya Ru II complexes promoted the one‐pot C=C/C=O bonds reduction of isoflavones using sodium formate as the hydrogen source through Asymmetric Transfer Hydrogenation‐Dynamic Kinetic Resolution (ATH‐DKR). Due to the neutral conditions employed, isoflavones with different substituents at the 2’‐position of B‐ring (H, OH, OMe and Br) were successfully reduced. Ten cis ‐3‐phenylchroman‐4‐ols were selectively obtained (>20 : 1 dr) in good yields (up to 86 %) and excellent enantioselectivities (up to >99 : 1 er). The synthetic applications of these chiral compounds were also demonstrated. Enantioenriched isoflavanones were obtained under mild metal‐free oxidation of the cis ‐3‐phenylchroman‐4‐ols while pterocarpans were synthesized by two strategies: an acid‐catalyzed cyclization and a novel approach based on a Pd‐catalyzed C−O intramolecular cross‐coupling reaction.