The reaction of 4-methyl-2-(methoxyphenyl)nicotinic acid with Eatons reagent (P2O5 - CH3SO3H) affords pyrido[3,2-c]coumarin derivatives or 1-methyl-4-azafluoren-9-ones depending on the position of the methoxy group on the benzene ring.
Keywords: Pyrido[3,2-c]coumarin, Eaton's reagent, methoxy group, 1-methyl-4-azafluoren-9-one, intramolecular cyclization