Synthesis, Crystal Structure and Biological Activity of Novel N‐substituted Diazabicyclo Derivatives

A series of N ‐substituted diazabicyclo derivatives were designed and synthesized based on the active subunit combination and structure–activity relationship theory. The compounds were prepared by levulinic acid or ester with diamine, then acylation with phenoxy acetyl chloride or acetoxy acetyl chloride. All the structures were characterized by IR, 1 H NMR, 13 C NMR, MS, and elemental analysis. The single crystal of compound 4a was determined by X‐ray crystallography. The preliminary bioassay showed that all products could protect soybean against injury caused by 2,4‐D butylate to some extent.