Abstract: The fluoride anion induced 1, 4 elimination of 2-[o-[l-(trimethylsilyl) alkyl] phenyl]-3, 3-dimethyloxazolidinium salts generates (E, E)-a-alkyl-a/-[2-(dimethylamino) alkyl]-0- quinodimethane intermediates, which are trapped stereoselectively with dienophiles to give polycycles. Intramolecular cyclization of 2-[o-[I-(trimethylsilyl) hept-6-enyl] phenyl]-3, 3- dimethyl-4-