Base-Promoted Annulation of α-Hydroxy Ketones and Dimethyl But-2-ynedioate: Straightforward Access to Pyrano[4,3-a]quinolizine-1,4,6(2H)-triones and 2H-Pyran-2,5(6H)-diones.

While 3-aryl-2-ketopropanols (X) exclusively give the pyrandiones (XI), 3-pyridyl derivatives give either pyrandiones (VII) and (IX) or pyranoquinolizinetriones (III) and (V) depending on the substitution pattern at the pyridine moiety.