Episodes from the Continuous Search for Solutions against Downy Mildew Diseases

Discovery background, lead optimization pathways, synthesis and structure-activity relationships of three different research projects searching for new active ingredients against downy mildew diseases are reported. These case studies, on which the author worked in three different decades in the research departments of Syngenta Crop Protection AG and its legacy company Novartis Crop Protection AG deal with inhibitors of cellulose synthase, tubulin polymerization and oxysterol-binding protein. Rarely used reactions, which have been applied within these projects, such as Seebach's variation of the Passerini reaction, the Bogert quinazoline synthesis and the carbonyldiimidazole-mediated Lossen rearrangement give proof of the significance of synthetic organic chemistry for modern crop protection.