Novel N-6-aryl-4-[(E)-2-furylmethylene]-1,2,3,4-tetrahydro-3-oxopyridazin-1 -ylcarbonyl}-p-toluene-sulfonamides 4a-d were prepared by the reaction of (E)-2-aroylmethyl-3-(2-furyl) acrylohydrazides 2a-d with tosylisocyanate. This has been shown to occur by initial formation of (E)-2-aroylmethyl-3-(2-furyl)-N'-(tosylaminocarbonyl) acrylohydrazides 3a-d followed by acid catalyzed cyclization to afford