Synthesis of functionalized 7-chloro-1,2,4-triazolo [4,3-a]quinoline

One carbon inserting agents transformed 6-chloro-2-hydrazinoquinoline (1) into the 2-functionalized 1,2,4-triazolo[4,3-a]quinoline skeleton. The 1-aryl and 1-pyridyl derivatives were prepared via condensation with aldehydes and then dehydrogenative ring closure. The 1-thiol group in 5 was introduced by reaction of 1 with carbon disulfide. Carboxy- and carboethoxy-methylation of 5 afforded the respective mercaptoacetic acid derivatives 6 and 8. Chlorination of 6 followed by dehydrative cyclization through its reaction with thiosemicarbazide afforded the respective amino thiadiazole derivative 7. Hydrazinolysis of 8 gave the corresponding hydrazide derivative 9. Compound 5 was reacted with acrylonitrile and acrylamide to give the corresponding cyano and carboxamido methylated derivatives 10 and 11. Under Mannich conditions, reaction of 5 with piperidine and morpholine afforded the respective Mannich bases 12 and 13. Reaction of 5 with acetobromoglucose gave the respective thioglucoside 14 which was deacetylated to 15. All compounds were screened for their antimicrobial activity against gram-positive and gram-negative bacteria.