“…1,2 These heterocycles have achieved significance in pharmacology as antibacterial, 3 antiviral, 4 antifungal, 5 anticancer, 6 anticonvulsant 7 and immunosuppressant agents. 8 Quite a plethora of methods have been developed for the preparation of these heterocycles including the condensation of carboxylic acids, 9 acid chlorides, 10,11 orthoesters, [12][13][14] esters, 15 and aldehydes [16][17][18][19][20][21] with o-aminophenols, o-aminothiophenols and o-phenylenediamines, dehydration of o-acylaminophenols, 22 the reaction of o-quinones with amines 23 and Beckmann rearrangement of o-acylphenoloximes.…”