THE REACTION OF 4-AMINOCOUMARIN WITH β-CARBONYL-SUBSTITUTED 4 Н -CHROMENES: SYNTHESIS OF 5 H -CHROMENO[4,3- b ]PYRIDIN-5-ONE DERIVATIVES
Reactions of 4 Н -chromene-3-carbaldehydes and 1 Н -benzo[ f ]chromene-3-carbaldehydes with 4-aminocoumarin were used to obtain a series of pyridocoumarin derivatives containing a 2-hydroxybenzyl or 2-hydroxy-1-naphthyl substituent at the β-position relative to the nitrogen atom. The reaction mechanism includes a Michael reaction, chromane ring opening, and cyclodehydration.