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.