Design, synthesis, fungicidal activities and structure-activity relationship studies of (-)-borneol derivatives containing 2-aryl-thiazole scaffold

A series of (-)-borneol derivatives containing 2-aryl-thiazole scaffold were designed, synthesized, and characterized by H-1 NMR, C-13 NMR, and HRMS. The fungicidal activities of these novel compounds against Fusarium oxysporum, Magnaporthe grisea, Botrytis cinerea, and Penicillium digitatum were evaluated. The results indicated that (1S,2R,4S)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl(Z)-4-oxo-4-(((2-phenylthiazol-4-yl)methyl) amino)but-2-enoate (6a) displayed potential fungicidal activities with broad spectrum. Especially, 6a exhibited an IC50 value of 48.5 mg/L against P. digitatum, which has higher fungicidal activity than commercial products hymexazol and amicarthiazol. Moreover, (1S,2R,4S)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl-4-oxo-4-(((2phenylthiazol-4-yl)methyl)amino)butanoate (5a) possesses an IC50 value of 24.3 mg/L against B. cinerea, comparable to hymexazol and far superior to amicarthiazol. Furthermore, the superficial structure-activity relationship was discussed, which might be helpful for discovering novel fungicides.