Synthesis of New 2H-Pyrano[3,2-h]quinolines With Potential Biological Activity

Abstract

5-Halo-8-hydroxyquinoline-7-carboxaldehyde 1a,b reacted with diethyl malonate to afford ethyl 6-halo-2-oxo-2H-pyrano[3,2-h]quinoline-3-carboxylates  2a,b. Michael addition followed by cyclisation of acetyl  acetone with 2a,b gave 1-acetyl-11-halo-2-methyl-4H,5H,4,5-dioxo-dipyrano[3,4-c,3`,2`-h]quinoline derivatives 3a,b. Compounds 2a,b were converted into their acid hydrazide 4a,b. Reaction of 4a,b with acetyl acetone produced 6-halo-3-(3`,5`-dimethyl-1H-pyrazole-1-carbonyl)-2H-pyrano[3,2-h]quinolin-2-ones 5a,b. Treatment of acid hydrazides 4a,b with isatin yielded 1H,2H-3-(2H-6-halo-2-oxo-pyrano[3,2-h]quinolin-3-carboxyhydrazono)-2-indolinones 6a,b which on cyclisation with Conc. H₂SO₄ afforded 3-[1,3,4-oxadiazino(5,6-b)indol-2-yl]-6-halo-2H-pyrano[3,2-h]quinolin-2-ones 7a,b. The biological screening was showed that pyrano[3,2-h] quinoline derivatives which containing pyrazole and indoline moieties have excellent antibacterial and antifungal activities.

Keywords: Quinoline, 2H-pyrano[3,2-h]quinoline, 8-hydroxyquinoline,microbial activity.