Noyori‐Ikariya RuII 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.
The Cover Feature illustrates the high reactive catalytic system for the Asymmetric Transfer Hydrogenation‐Dynamic Kinetic Resolution (ATH‐DKR) of isoflavones obtained by the entanglement of Noyori‐Ikariya Ru(II) complexes and sodium formate as the hydrogen source. The central couple in the image are served an isoflavone in a tray representing how mild and neutral conditions allow the ATH‐DKR reaction of several isoflavones with different substituents in the 2'‐position to proceed. The outside panel shows the general reaction diagram by which ten cis‐3‐phenylchroman‐4‐ols (>20:1 dr) in good yields (up to 86%) and excellent enantioselectivities (up to >99:1 er) were obtained. The framed structures (inside) represent the synthetic applications of these chiral compounds. In their Full Paper, F. V. Gaspar et al. obtained enantioenriched isoflavanones 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. More information can be found in the Full Paper by F. V. Gaspar et al.
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