Cover Feature: Enantioselective Synthesis of Isoflavanones and Pterocarpans through a Ru^II‐Catalyzed ATH‐DKR of Isoflavones (ChemCatChem 24/2021)

Abstract

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.