Chemistry of clothianidin and related compounds

Clothianidin, a neonicotinoid insecticide, has been found by former Agro Division, Takeda Chemical Industries, Ltd. (Sumitomo Chemical Co., Ltd., at present) and codeveloped with Bayer CropScience. During the studies on neonicotinoid insecticides, nitenpyram (an open-chain nitromethylene derivative) was prepared first, showing a potent activity against Hemiptera and Thysanoptera pests, and its modification led to clothianidin (a nitroguanidine derivative). Clothianidin exhibits excellent control efficacies in small amounts for a wide variety of insect pests such as Hemiptera, Thysanoptera, Coleoptera, Lepidoptera, and Diptera for the long term, with excellent systemic action and by a variety of application methods. The structural features of clothianidin are a thiazole ring and an open-chain guanidine skeleton. The structure-activity relationships of guanidine derivatives and the synthetic studies of clothianidin are also discussed.