Syntheses employing pyridyllithium reagents: new routes to 2,6-disubstituted pyridines and 6,6′-disubstituted 2,2′-bipyridyls

New 2,6-disubstituted pyridine derivatives have been synthesized employing 6-bromo-2-lithiopyridine as an intermediate. Subsequent replacement of the 6-bromine can be effected by metal-halogen exchange or other reactions in some cases. Reactions of the previously unreported 6-lithio-2,2′-bipyridyl and 6,6′-dilithio-2,2′-bipyridyl are described. Cupric chloride was found to be an effective coupling agents for lithiopyridine reagents, allowing facile and high yield syntheses of substituted 2,2′-bipyridyls.