Bromo-directed N-2 alkylation of NH-1,2,3-triazoles: efficient synthesis of poly-substituted 1,2,3-triazoles.

Reaction of 4-bromo-NH-1,2,3-triazoles 2 with alkyl halides in the presence of K(2)CO(3) in DMF produced the corresponding 2-substituted 4-bromo-1,2,3-triazoles 5 in a regioselective process. Subsequent Suzuki cross-coupling reaction of these bromides provided an efficient synthesis of 2,4,5-trisubstituted triazoles 3. In addition, reduction of the bromotriazoles by hydrogenation furnished an efficient synthesis of 2,4-disubstituted triazoles 8.