Synthesis and Pesticidal Properties of Thio and Seleno Analogs of Some Common Urea Herbicides

Thio and seleno analogs of fenuron, isoproturon, chlorotoluron, metoxuron, monuron, and diuron were synthesized from the corresponding aryl amines. Their reaction with thiophosgene leads to isothiocyanates. Aryl amines were also converted (via isocyanides) to isoselenocyanates. The reaction of both isothio- and isoselenocyanates with dimethylamine affords the corresponding thio and seleno analogs of the above-mentioned urea herbicides. Herbicidal activity of the synthesized compounds was slightly lower than the activity of the parent urea herbicides. The thio and seleno analogs as well as the parent ureas showed good fungicidal activity at a concentration of 200 ppm against selected fungi.     

Synthesis of 5-methylidene-2-thio- and 2-selenohydantoins from isothiocyanates or isoselenocyanates and l-serine

3-Aryl-5-methylidenethiohydantoins and 3-aryl-5-methylidene-selenohydantoins were obtained by one-pot reaction of aryl isothiocyanates or isoselenocyanates with l-serine in NaOH–H₂O–Py mixture followed by room temperature HCl-promoted dehydration.