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

Abstract

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.