Continuous‐Flow Asymmetric Hydrogenation for the Synthesis of an (S)‐Metolachlor Intermediate Using Catalysts Immobilized on a Core/Shell‐Type Support

Abstract

AbstractHere we show continuous‐flow synthesis of a key inter‐mediate of (S)‐Metolachlor, which is a widely used agrochemical that is in huge demand, with asymmetric hydrogenation using a heterogeneous catalyst immobilized on a core/shell‐type support. We have immobilized a homogeneous catalyst onto a core/shell‐type heterogeneous support that was developed in our laboratory, which showed high turnover frequency and turnover number over a long period (over 120 h) when used in a solvent‐free continuous‐flow manner. This result demonstrates the feasibility of continuous‐flow production of chiral agrochemicals with packed‐bed heterogeneous catalysts. Moreover, the heterogenization protocol was shown to be applicable to elaborate practical catalysts used in industry, especially the group of phosphine ligands.