Pyrazolo[3,4-d]pyrimidin-4-one derivatives bearing an aniline group: design, synthesis and antifungal activity

Abstract

Detecting novel agricultural fungicides has be regarded as the important safeguard for maintaining the development of sustainable agriculture. Aiming to develop novel candidates of agricultural fungicides, the 3-(phenylamino)quinazolin-4(3H)-one emerging as a known antifungal skeleton was modified by assimilating a pyrazole fragment to construct nineteen novel pyrazolo[3,4-d]pyrimidin-4-one derivatives bearing an aniline group. After structural confirmations, the obtained pyrazolo[3,4-d]pyrimidin-4-one derivatives were evaluated for their antifungal activities against Fusarium graminearum, Rhizoctonia solani, Botrytis cinerea and Alternaria solani. The above antifungal bioassays indicated that some pyrazolo[3,4-d]pyrimidin-4-one derivatives bearing a bulky electronegative unit at the ortho-position of an aniline scaffold could exhibit the conspicuous antifungal effect against F. graminearum. Among them, the anti-F. graminearum EC₅₀ value of a target compound 5m was measured as 5.61 μg/mL, which is distinctly superior to that of hymexazol (56.19 μg/mL). The above results provided a necessary replenishment for discovering novel antifungal leads owing the development prospect on effectively controlling Fusarium head blight.

Graphical abstract