Synthesis, herbicidal activities, and 3D-QSAR of 2-cyanoacrylates containing aromatic methylamine moieties

A series of novel 2-cyanoacrylates containing different aromatic rings were synthesized, and their structures were characterized by (1)H NMR, elemental analysis, and single-crystal X-ray diffraction analysis. Their herbicidal activities against four weeds and inhibition of photosynthetic electron transport against isolated chloroplasts (the Hill reaction) were evaluated. Both in vivo and in vitro data showed that the compounds containing benzene, pyridine, and thiazole moieties gave higher activities than those containing pyrimidine, pyridazine, furan, and tetrahedronfuran moieties. To further explore the comprehensive structure-activity relationship on the basis of in vitro data, comparative molecular field analysis (CoMFA) was performed, and the results showed that a bulky and electronegative group around the para-position of the aromatic rings would have the potential for higher activity, which offered important structural insights into designing highly active compounds prior to the next synthesis.