2-Arylhydrazononitriles as building blocks in heterocyclic synthesis: A novel route to 2-substituted- 1,2,3-triazoles and 1,2,3-triazolo[4,5-b]pyridines

• Saleh M. Al-Mousawi and
• Moustafa Sh. Moustafa

Beilstein J. Org. Chem. 2007, 3, No. 12, doi:10.1186/1860-5397-3-12

• . Instead the hydrolyzed product 5 was formed. Introduction Interest in 1,2,3-triazole chemistry has recently been revived. [1][2][3][4] Zaprinast (1) is used as cyclic AMP phosphodiasterase inhibitor. [5] Plenty of 1,2,3-triazoles have also been reported to have useful pharmaceutical potential. [6][7][8

• ][9] Synthetic approaches to 1,2,3-triazoloazines are rather limited. There are in fact few known routes to 4-functionally substituted 1,2,3-triazole-5-amines. [7] The latter is one of the logical starting points for condensed 1,2,3-triazoloazines. In the present article we provide a versatile route

• . Formation of amidooximes on reacting 2-arylhydrazononitriles with hydroxylamine hydrochloride under similar conditions has been reported earlier by Elnagdi et al. [10][11] Attempted cyclization of 3 into 1,2,3-triazole via reflux in acetic anhydride, as has been reported recently, [11] afforded a product