Synthesis of new quinoline derivatives as antimicrobial agents

2-Hydroxyquinoline-4-hydrazide was condensed with some aromatic aldehydes and acetophenones to give the hydrazones 1a-h. It was also reacted with HCOOH, PhCOCl and p-CH3O-PhCOCl to afford 2a-c. Cyclization of 2b was completed by using PPA, POCl3 and/or P2S5, which gave compounds 3, 4, and 6 respectively. Reaction of 4 with some amines gave the corresponding derivatives 5a-f. The thiosemicarbazide 7 was cyclized under acid and basic condition to give the thiadiazolyl-8 and triazolyl-10 derivatives.