Stereoselective synthesis and biological activities of diethyl ( E )‐{[4‐cyano‐5‐[[(disubstitutedamino)methylene]amino]‐3‐(methylthio)‐ 1 H ‐pyrazol‐1‐yl]substituited phenylmethyl}phosphonates

Diethyl {[5‐amino‐4‐cyano‐3‐(methylthio)‐1 H ‐pyrazol‐1‐yl]substitutedphenylmethyl}phosphonates 3 were efficiently synthesized via the condensation of [(1‐hydrazino)substitutedphenylmethyl]phosphonates 1 with 2‐[bis(methylthio)methylene]malononitrile 2 . 3 reacted with triethyl orthoformate to afford diethyl ( E )‐{[4‐cyano‐5‐[(ethoxymethylene)amino]‐3‐(methylthio)‐1 H ‐pyrazol‐1‐yl]substitutedphenylmethyl}phosphonates 4 , which reacted with various secondary amines at room temperature to provide the target compounds 5 in good yields. Their structures were confirmed by ir, 1 H and 31 P NMR, mass spectroscopy, and elemental analyses. The results of preliminary bioassay indicated that compounds 5 possess potent herbicidal activity against the roots of dicotyledonous (oil rape) plants at the dosage of 100 mg/L, and compounds 5c and 5g exhibit 80.8% and 76.7% inhibitory activity against Colletotrichum gossypi at the concentration of 50 mg/L, respectively. Abstract end data: J. Heterocyclic Chem., 46, 555 (2009).