A facile synthesis of new fungitoxic peptidyl imidazo[2,1-b]-1,3,4-oxadiazoles

The reaction of 5-aryl-2-arylideneamino-1,3,4-oxadiazole (5a-d) with trichloroacetic acid followed by ring closure of the isolable intermediates, 5-aryl-2-[(1-aryl-2,2,2-trichloroethyl) amino]-1,3,4-oxadiazoles (6a-d), with dipeptides (gly.gly and L-ala. gly) yields new 2,6-diaryl-5-peptidyl (gly.gly and L-ala.gly)imino-5,6-dihydroimidazo-[2,1-b]-1,3,4-oxadiazoles. Two of the compounds (8d and 8h) displayed the in vitro fungitoxicity equivalent to that of a commercial fungicide Mancozeb against A. solani and F. oxysporum at 1000 ppm concentration.