Enantioselective Catalysis for Agrochemicals: The Case History of the DUAL MAGNUM® Herbicide

Abstract

The use of enantioselective catalytic methods for the technical preparation of chiral agrochemicals is illustrated by the case history of the herbicide (S)-merolachlor (trade name DUAL MAGNUM®). The key step for the technical synthesis of the enantiomerically enriched compound is the asymmetric hydrogenation of an imine intermediate, made possible by a new iridium-ferrocenyldiphosphine catalyst system. Important aspects of the development of the catalyst system as well as minimal prerequisites for the use of enantioselective catalysts for the production of agrochemicals are discussed.