Abstract: Compounds of formula I ##STR1## wherein A denotes a group having an electron acceptor character;Az denotes a group for completing a 5-membered heteroaromatic ring (azole ring) to which a 5- or 6-membered carbocyclic or heterocyclic ring may be attached by condensation andQ denotes a group for completing a condensed benzene or pyridine ringare prepared by oxidizing a compound of formula II ##STR2## wherein A and Q have the meanings indicatedwith an oxidizing agent which transfers acyloxy groups and then reacting the product with a compound of formula III ##STR3## wherein Az has the meaning indicated.