The Synthesis of Pyrethroids

We provide here a comprehensive review of the synthetic methods for pyrethroid insecticides in both the commercial pesticide market and scientific research. Pyrethroids are derived from natural pyrethrins, which are extracted from pyrethrum plants. However, due to limited production from natural sources, synthetic pyrethroids have become essential to meet global demand. The review begins by introducing the structures of natural pyrethrins and their key active components, followed by a detailed discussion of the synthetic methods based on different chrysanthemic acid starting materials. The review is divided into five sections, covering the synthesis of pyrethroids from dimethyl chrysanthemic acid, chrysanthemic acids bearing halogenated alkenyl groups, chrysanthemic acids with acrylate fragments, pyrethroids containing other types of cyclopropyl groups, and noncyclopropyl pyrethroids. Each synthetic method is elaborated with specific reaction pathways and intermediates accompanied by examples of commercially available pyrethroids. Insights into future directions for the development of novel pyrethroid structures are also provided at the end of this review based on our own perspectives.