In searches for novel photosensitive [1] and biologically active materials [2-4] a broad series of 1,3,4-oxa- diazoles with different substituents on the carbon atoms have been reported. The usual basis for their synthesis is mainly the dehydration of the corresponding acid hydrazides [5]. However, this reaction is done in relatively severe conditions and does not permit preparation of polynuclear systems with different proportions of oxadiazole rings and other ...