Synthesis of 3-ethoxycarbonyl-4-hydroxyquinoline N-oxides from the Baylis-Hillman adducts of o-nitrobenzaldehydes
[reaction: see text] The reaction of the Baylis-Hillman adducts la-e of o-nitrobenzaldehydes and trifluoroacetic acid at 60-70 degrees C gave 3-ethoxycarbonyl-4-hydroxyquinoline N-oxide derivatives 3a-e in good to moderate yields.