Organocatalytic Enantioselective Michael Addition of Pyrazol‐5‐ones to β‐Silylmethylene Malonates: Synthesis of Chiral Organosilanes Under Metal‐ free Conditions

Abstract

AbstractHerein, we report a Michael addition reaction of pyrazolin‐5‐ones with β‐silylmethylene malonates using a squaramide catalyst derived from quinidine under mild reaction conditions. This protocol delivered chiral organosilanes appendage with pyrazole moiety in high yields (up to 90%) and good to excellent enantioselectivities (up to 98 : 2 er). A quinine derived thiourea catalyst deliver corresponding antipode for enantiomers with almost similar level of yields (up to 93%) and good to excellent enantioselectivities (up to 2 : 98 er). The scale‐up reaction for synthesis of two chiral organosilanes confirmed the practical reliability of this protocol.