Synthesis of Five-Membered Ring Heteroaryl Pyridines from Heteroaryllithium and N-Ethoxycarbonylpyridinium Chlorides

Furylpyridines, thienylpyridines, and imidazolylpyridines were obtained regioselectively in 40-67% yields from the reaction of heteroaryllithiums with N-ethoxycarbonylpyridinium chloride or N-ethoxycarbonyl-3-methylpyridinium chloride in the presence of Cul in a catalytic amount at ?78 °C or ?50°C, then followed by oxidation. The regioselectivity of this reaction depended upon temperature of the reaction and the nature of heteroaryllithiurn.