Efficient synthesis of N-2-aryl-1,2,3-triazole fluorophores via post-triazole arylation.

Efficient post-triazole regioselective N-2 arylation was developed from C-4, C-5 disubstituted-1,2,3-NH-triazoles. Three different approaches had been investigated, including S(N)Ar, Cu(I) catalyzed aryl amidation and Cu(II) mediated boronic acid coupling. The N-2-aryl triazoles were successfully synthesized with excellent yields. The structures were characterized by X-ray crystallography and some N-2-triazole products gave strong fluorescence with various emission controlled by the C-5 groups.