Abstract
A series of 4-unsubstituted fused quinoline derivatives, including the biologically significant 5-deazaflavin analogs and 6H-chromeno[4,3-b]quinolin-6-ones, were synthesized from easily accessible N-(2-aminobenzylidene)-4-methylanilines and heterocyclic 1,3-dicarbonyl compounds. The reaction was carried out in water in the absence of any catalyst to access the products in high yields. The complications associated with the stability of 2-aminoarylaldehydes were resolved by using the stable equivalent N-(2-aminobenzylidene)-4-methylanilines.