Design and Discovery of Novel Chiral Antifungal Amides with 2-(2-Oxazolinyl)aniline as a Promising Pharmacophore

Inspired by established succinate dehydrogenase inhibitors (SDHIs), our continuing efforts toward the discovery of chiral antifungal amides turned to the optimization of their polar regions with 2-(2-oxazolinyl)aniline as a known pharmacophore. Scaffold hopping and bioactivity-guided convergent synthesis enabled the identification of promising antifungal categories. Fine tuning of the substituents and chirality furnished seven amides (1s, 1t, 2d, 2h, 2j, 3k, and 21) as antifungal candidates, with EC50 values lower than 5 mg/L. The first investigation of chiral amides of acyclic acids as SDHIs was conducted, and compound 2d was selected as a promising candidate against Botrytis cinerea, with a preventative efficacy of up to 93.9% at 50 mg/L, which is better than that of boscalid. The different binding models between compounds with different configurations were simulated for compound 2d and its diastereoisomers. The benefits of synthetic accessibility and cost-effectiveness highlight the practical potential for compound 2d as a good alternative to known SDHI fungicides.