Unlocking the Phosphoric Acid Catalyzed Asymmetric Transfer Hydrogenation of 2-Alkenyl Quinolines for Efficient Flow Synthesis of Hancock Alkaloids

Abstract

Chiral tetrahydroquinolines are present in several bioactive molecules, such as the Hancock alkaloids. Although the organocatalytic asymmetric transfer hydrogenation of 2-aryl quinolines has emerged as a safer alternative to using hydrogen gas, analogous reactions with 2-alkenyl quinolines remain unexplored. Here we present a protocol to synthesize key enantioenriched intermediates to the Hancock alkaloids, providing a constant outcome for, at least, a 24 h continuous flow operation.