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The Michael addition of enaminoesters to coumarins ( 1 ) does not lead to the formation of simple adducts  3  but to the rearranged 4-aryl-2-pyridone  4a . Now,  N -carbamoylation of the 6-amino-2-pyridone  4a  with alkyl isocyanates and further transformation of the corresponding novel ureido-2-pyridone derivatives  6a–g  into chromeno[3,4- c ]pyridines  5d , g  and  O -acetyl derivatives  7a–g  are reported. All newly synthesized compounds were characterized by means of  1 H/ 13 C NMR, MS, IR spectra and elemental analysis. The structure of the ureide  6f  and of the  N -cyclohexyl- O -acetyl derivative  7g  were additionally confirmed by crystal structure determinations. Acute toxicity after intraperitoneal administration, blood clotting time, analgesic activity and the effects on the hexobarbital sleeping time were tested on laboratory animals (compounds  4a ,  6a ,  6c ,  6d  and  6g ).

Synthesis of some 6-alkylureido-4-aryl-2(1 H )-pyridones: further transformations and pharmacological activity