Synthesis of some N1-phenyl-N3-[2-aryl/aryloxymethyl-1,3,4-oxa(thia)diazol-2-yl]sulphonyl ureas as potential pesticides.

N1-Phenyl-N3-aryl/aryloxymethyl[1,3,4-oxa(thia)diazol-2-yl]s ulphonyl ureas (4 and 7) were conveniently prepared from 2-aryl/aryloxymethyl- 1,3,4-oxa(thia)diazol-2-sulphonamide (3 and 6) and phenyl isothiocyanate. Sulphonamides were synthesised by the reaction of 2-aryl/aryloxymethyl-1,3,4-oxa(thia)diazol-2-sulphonyl chlorides (2 and 5) with ammonia. All the compounds have been tested for fungicidal activity against the fungal species Cephalosporium saccharii and Helminthosporium oryzae. The two species of the aquatic fungi viz. Saprolegnia parasitica and Achlya orion responsible for fish mycoses were tested and also found remarkably active. All the compounds were also tested for herbicidal activity against Digiteria ciliaris, Oryza sativa and Raphunus sativa.