Construction of spiro-1,2,4-oxadiazoline-fused matrine-type alkaloids as pesticidal agents

Abstract In order to increase the agricultural properties of matrine, a series of novel matrine-type alkaloids containing spiro-1,2,4-oxadiazoline fragment at the C-15 position were prepared. Eight target molecules were elucidated by X-ray single-crystal diffraction. The antifeedant activities of Ig and IIIh against Mythimna separata Walker were>1.7 folds of the precursor matrine. The acaricidal activities of Ij, IIe, IIg, IIi and IIIa against Tetranychus cinnabarinus Boisduval were 2.6–3.7 folds of matrine. Especially IIg (R1 = R2 = 4-Cl) and IIi (R1 = 4-Cl; R2 = 4-Br) exhibited the pronounced antifeedant and acaricidal activities. SARs showed that their pesticidal activities were related to the substitutents and their positions on the phenyl rings at the C-3 and N-4 positions of 1,2,4-oxadiazoline skeleton.