Cinchona‐Based Hydrogen‐Bond Donor Organocatalyst Metal Complexes: Asymmetric Catalysis and Structure Determination

Abstract

Abstract In this study, we describe the synthesis of cinchona (thio)squaramide and a novel cinchona thiourea organocatalyst. These catalysts were employed in pharmaceutically relevant catalytic asymmetric reactions, such as Michael, Friedel–Crafts, and A3 coupling reactions, in combination with Ag(I), Cu(II), and Ni(II) salts. We identified several organocatalyst‐metal salt combinations that led to a significant increase in both yield and enantioselectivity. To gain insight into the active catalyst species, we prepared organocatalyst‐metal complexes and characterized them using HRMS, NMR spectroscopy, and quantum chemical calculations (B3LYP‐D4/def2‐TZVP), which allowed us to establish a structure‐activity relationship.

Keywords

• metal complex
• cinchona
• hydrogen-bond donor
• asymmetric catalysis
• structure elucidation