Design, Synthesis, and insecticidal Activity of Novel Pyrazole Derivatives Containing lagio(a)usp.br.α-Hydroxymethyl-N-benzyl Carboxamide, α-Chloromethyl-/V-benzyl Carboxamide, and 4,5-Dihydrooxazole Moieties

摘要

On the basis of commercial insecticides tebufenpyrad and tolfenpyrad, two series of novel pyrazoIe-5-carboxamides containing α-hydroxymethyl-N-benzyl or α-chloromethyl-N-benzyl and pyrazoles containing 4,5-dihydrooxazole moieties were designed and synthesized via the key intermediate 2-amino-l-(4-substituted) phenyl ethanol. The structures of target compounds were confirmed by ~1H NMR and elemental analysis or high-resolution mass spectrum (HRMS), and their activities against cotton bollwonn (Helicoverpa armigera), diamondback moth (Plutelta xylostella), bean aphid (Aphis craccivora), mosquito (Culex pipiens pallens), and spider mite (Tetranychus cinhabarinus) were tested. The results of bioassays indicated that compounds containing α-chloromethyl-N-benzyl and compounds containing 4,5-dihydrooxazole showed high insecticidal activity against cotton bollwoim. Especially, stomach activities of compounds Ij, II, and lIe were 60% at 5 mg kg~(-1). Moreover, the target compounds exhibited high selectivity between cotton bollworm and diamondback moth, although both of them belong to the order Lepidoptera. Although the activities against diamondback moth were at a low level, some of the target compounds exhibited antifeedant activity. The compounds also had good activities against bean aphid, mosquito, and spider mite. The foliar contact activity of compounds Ic, Id, Ie, and IIf against bean aphid were 95, 95,100, and 95%, respectively, at 200 mg kg~(-1). The mitiddal and oyicidal activities of compound Hi against spider mite were both 95% at 200 mg kg~(-1). Furthermore, a trivial change at 4-position of pyrazole ring would lead to great changes in properties and activities, which can easily be deduced by comparing the activities of compounds in series I (4-chloro-pyrazole compounds) with corresponding compounds in series II (4-hydro-pyrazole compounds), especially from the mitiddal and ovicidal activities of Ii and Hi against spider mite.