Regioselective C-4 deprotonation of 3-bromopyridine, followed by Li/Zn transmetalation and Pd-mediated coupling processes, provides a flexible entry to 4-substituted and 3, 4- disubstituted pyridines. Application of a similar sequence to 2-bromopyridine (with LDA as base) provides 2, 3-disubstituted pyridines, but using lithium 2, 2, 6, 6-tetramethylpiperidide (LiTMP) provides access to both the 2, 3-and 2, 4-disubstituted isomers.
