Application of Molecular-Modeling, Scaffold-Hopping, and Bioisosteric Approaches to the Discovery of New Heterocyclic Picolinamides.

Macrocyclic natural products and their derivatives are a valuable source for biologically active crop protection products and have had significant impact on the development of conventional agrochemicals. However, they can be challenging starting points for lead-generation efforts because of their size, structural complexity, and developability. Using molecular modeling and electrostatic analysis, alternative bicyclic isosteres were identified as replacements for the antifungal nine-membered macrocycle UK-2A. By application of a structure-based conformational approach, a series of heterocyclic replacements were derivatized to deliver promising fungicidal activity and scaffold bioisosteres were further diversified to investigate structure-activity relationships.