A Base-Controlled Reaction of 2-Cyanoacetamidines (3,3-Diaminoacrylonitriles) with Sulfonyl Azides as a Route to Nonaromatic 4-Methylene-1,2,3-triazole-5-imines

Reactions of 2‐cyanoacetamidines with sulfonyl azides were shown to take place via two different pathways to form a mixture of 1‐substituted 5‐amino‐1,2,3‐triazoles 3 and novel 4‐methylene‐1H‐1,2,3‐triazole‐5(4H)‐imine derivatives 4–14. In the absence of a base, 5‐amino‐1,2,3‐triazoles 3 are formed as the only products. The presence of 1.2 equiv. of sodium ethoxide or DBU switches the reaction outcome while involving the cyano group, resulting (after a 1,5‐protic shift) in triazoles 4–14 as the only products. The methods were elaborated for the selective and efficient synthesis of triazoles 3 and 4‐methylene‐1,2,3‐triazole‐5‐imines 4–14 including one‐pot synthesis from sodium azide and sulfonyl chlorides. The unusual structure of 4–14 compounds was confirmed by X‐ray data and 2D ¹H–¹⁵N and ¹H–¹³C NMR spectra. The formation of the products was explained by the presence of two strong hydrogen bonds N···H and O···H in these molecules.