Synthesis and herbicidal activity of <i>O,O</i>‐dialkyl <i>N</i>‐[2‐(5,7‐dimethyl‐[1,2,4]triazolo[1,5‐a]pyrimidin‐2‐yloxy)benzoxyl]‐1‐amino‐1‐substitutedbenzyl phosphonates

Abstract

Abstract magnified image A series of novel 1,2,4‐triazolo[1,5‐a]pyrimidine derivatives containing an α‐amino phosphonate moiety 5 were designed and synthesized by the multi‐step reactions. Their structures were clearly confirmed by spectroscopic data (IR, 1 H NMR, 31 P NMR, MS) and elemental analysis, compound 5b was further determined by X‐ray diffraction crystallography. The results of preliminary bioassay indicated that some of the title compounds 5 possessed moderate herbicidal activities against dicotyledonous plants ( Brassica campestris L ) at the concentration of 100 mg/L. For example, compound 5i possessed 92.0% inhibitory activity against B. campestris L and showed better activity than that of the commercialized herbicide Bispyribac‐sodium; however, compounds 5 displayed weak herbicidal activity at the concentration of 10 mg/L. J. Heterocyclic Chem., (2010).