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. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim