Diels-Alder cycloadditions using nucleophilic 2-pyridones. Regiocontrolled and stereocontrolled synthesis of unsaturated, bridged, bicyclic lactams

Abstract

Captodative 3-oxy- and 3-(tolylthio)-1-tosyl-2-pyridones 1a-1d are shown to be reactive as nucleophilic dienes undergoing 2+4-cycloadditions with various electrophilic alkenes under sufficiently mild thermal conditions (90-100 o C) that the initial bicylic lactam adducts can be vilated on gram scale in fair to very good yields (23-83%) without loss of an isocyanate from the heteroatom bridge. These bicyclic adducts are formed with complete regiocontrol and stereocontrol