[Chemical and pharmacological research on pyran derivatives. XIV. 3-alkylaminoaphtho/2,1-b/pyran-1-ones and derivatives].

3-Alkyl(phenyl)aminoaphtho[2,1-b]pyran-1-ones (III) were prepared from N-alkyl or N-phenylethoxycarbonylacetamides and 2-naphthol in the presence of phosphorus oxychloride, in order to evaluate their pharmacological activity on the CNS in comparison with previously described 3-dialkylaminoaphtho[2,1-b]pyran-1-ones. Compounds (III) gave 2-morpholinomethyl derivatives as well as N-acetyl and N-ethtoxycarbonyl derivatives. The reaction of (III) in which R = alkyl and N,N-dimethylformamide-POCl3 afforded 2-formyl derivatives and in some cases also 8-alkyl-9,10-bisdimethylaminoaphtho[1',2':5,6]pyrano[2,3-b]pyrrol-11(8H)-ones; when R = phenyl, only naphtho[1',2':5,6]pyrano[2,3-b]quinolin-14-one was obtained from the same reaction. Pharmacological evaluation showed that compounds (III) had a weak CNS depressant activity. Some of them also exhibited antagonist effect on reserpine-induced blepharospasm and hypothermia and on metrazole-induced seizures in the mouse. Within the limits of these activities a special behavior was found for the compound 3-ethylaminoaphtho[2,1-b]pyran-1-one [(III b) - K 12479].