The present invention relates to novel nitrone compounds of formula (I),wherein, A, A1, R1, R2, R3,R4and n are as defined in the description. The present invention further relates to their preparation and use to protect crops against undesired phytopathogenic microorganisms, phytopathogenic fungi and pests such as nematodes.本發明涉及式(Ⅰ)的新型硝酮化合物,其中,A、A1、R1、R2、R3、R4和n如描述中所定義。本發明進一步涉及其製備方法,以及其用於保護農作物免受有害植物致病微生物、植物致病真菌和線蟲等害蟲的侵害的用途。