Chirality and Crop Protection

Abstract The modern agrochemical industry is searching, more intensively than ever, for new substances to combat pests (weeds, deleterious insects, plant pathogens, etc.). In the complex and costly selection and optimization process, state‐of‐the‐art scientific methods are always needed. The aims of the interdisciplinary optimization are mainly the reduction of the rate of application of the new substance, an increase in the selectivity against the target organism, and the optimal ecological profile. If a promising crop protection compound is a racemate or a diastereoisomeric mixture, the chemist has a unique opportunity to contribute to this optimization process through the synthesis of enantiomerically pure isomers for testing purposes. If the single isomer proves to be biologically superior to the racemate, the development of an economical and ecologically sound process for the production of the single isomer presents an even greater challenge. The average price of a crop protection compound is much lower than that for a pharmaceutical product, and this fact imposes a severe limitation upon the flexibility of the chemist who is concerned with the synthesis and production of a stereochemically pure agrochemical. This forces the crop protection chemist to make full use of both his scientific and creative capabilities. Fortunately, parallel to the development of the above optimization aims of a modern and ecologically sound crop protection research, there has been a continuous and worldwide advance in the area of asymmetric synthesis. Due to the interplay of these two parallel efforts there has been a great accumulation of chemical, biological, and agronomical knowledge in recent years, which should have implications beyond merely the synthesis of enantiomerically pure agrochemicals.