PREPARATION OF NEW NITROGEN-BRIDGED HETEROCYCLES .39. ONE-POT SYNTHESIS OF 2H-PYRANO[3,2-A]INDOLIZIN-2-ONE DERIVATIVES

Various ethyl 2-(3-cyanoallylidene)- or rbonyl)allylidene]-1,2-dihydro pyridin-1-ylacetates were prepared from the reactions of 1-(1-ethoxyca rbonylalkyl)-2-methylpyridinium halides with activated ethoxymethylide ne compounds in the presence of a base. The treatment of these 2-allyl idene-1,2-dihydropyridine derivatives with acetic acid at the reflux t emperature gave directly the title compounds in low to moderate yields .