Synthesis, crystal structure, and biological evaluation of a novel eight-membered dinitration neonicotinoid analogues

In the studies on dihydroxy intermediate synthesis, a serendipitous reaction of introducing nitro group from nitromethylene has been observed. Instead of expected dihydroxy compounds, dinitration structures with nitromethylene analogues were prepared under mild conditions by using a metal-free catalyst B(OH)₃. In this reaction, the extra nitro group was suggested to be from starting material. Bioassays indicated that compound 3a showed good insecticidal activities against cowpea aphid (Aphis craccivora) and armyworm (Mythimna separata), with LC₅₀ values were 4.9 mg/L and 7.1 mg/L, respectively.