Regioselective cross-coupling reactions of boronic acids with dihalo heterocycles.

The carboxylic acid anion moiety has been used as a tunable directing group in the cross-coupling reaction of 2,6-dichloronicotinic acid and 2,5-dibromo-1,2,4-triazole derivatives producing selectively the 2- or 6-substituted nicotinic acids, while only the 5-substituted triazoles were obtained under a variety of conditions.