1,2,3-Triazoles as leaving groups in SNAr-Arbuzov reactions: synthesis of C6-phosphonated purine derivatives.

A new method for C-N bond transformations into C-P bonds was developed using 1,2,3-triazoles as leaving groups in SNAr-Arbuzov reactions. A series of C6-phosphonated 2-triazolylpurine derivatives was synthesized for the first time, with the isolated yields reaching up to 82% in the C-P-bond-forming event. The SNAr-Arbuzov reaction of 2,6-bistriazolylpurines follows the general regioselectivity pattern of the C6-position being more reactive towards substitution, which was unambiguously proved by X-ray analysis of diethyl (9-heptyl-2-(4-phenyl-1H-1,2,3-triazol-1-yl)-9H-purin-6-yl)phosphonate.