SYNTHESIS OF 5-MEMBERED RING HETEROARYL PYRIDINES FROM HETEROARYLLITHIUM AND N-ETHOXYCARBONYLPYRIDINIUM CHLORIDES

Furylpyridines, thienylpyridines, and imidazolylpyridines were obtaine d regioselectively in 40-67% yields from the reaction of heteroaryllit hiums with N-ethoxycarbonylpyridinium chloride or N-ethoxycarbonyl-3-m ethylpyridinium chloride in the presence of Cul in a catalytic amount at -78-degrees-C or -50-degrees-C, then followed by oxidation. The reg ioselectivity of this reaction depended upon temperature of the reacti on and the nature of heteroaryllithium.