Preparation of 4-ethoxy-2,3-dihydropyridinium salts 3a,c,d [6] was accomplished in high conversion utilizing ethyl Meerwein's reagent [7] as determined by ¹ H NMR analysis. In situ identification of the 4-ethoxy-2,3-dihydropyridinium tetrafluoroborate salts was accomplished via ¹ H NMR spectroscopy. Central to the identification of the dihydropyridinium salts was the ¹ H NMR signal representing the vinylic proton H a (Table [¹] ). The 4-ethoxy-2,3-dihydropyridinium salts 3 ...
