Convenient synthesis of 4<i>H</i>-chromenyl-tetrahydro-2<i>H</i>-pyrancarboxylates and cleavage of chromone and pyran rings leading to 5-(2-hydroxybenzoyl)-2-(trifluoromethyl)-1,2-dihydropyridine-3-carboxylates

<p>4<i>H</i>-Chromenyl-tetrahydro-2<i>H</i>-pyrancarboxylates <b>3a–k</b> have been conveniently prepared by the reaction of 3-formylchromones <b>1a–k</b> and ethyl 4,4,4-trifluoro-3-oxobutanoate <b>2a</b> with good yields. Thus obtained 4<i>H</i>-chromenyl-tetrahydro-2<i>H</i>-pyrancarboxylates <b>3a–k</b> were reacted with amines <b>4a–e</b> to provide series of 5-(2-hydroxybenzoyl)-2-(trifluoromethyl)-1,2-dihydropyridine-3-carboxylates <b>5a–o</b>. The reaction proceeded via Michael addition (C-N bond formation) and followed by cleavage of chromone and pyran rings (C-O bond cleavage) in one pot.</p>