Isomerization of trialkylidene(arylidine) triaminoguanidines to 4,5-dihydro-1,2,4-triazole derivatives

Derivatives of the Triaminoguanidinium Ion, 2. Prototropic Tautomerism, Crystal and Molecular Structure of N,N´,N´´-Tris(propan- 2-iminyl)guanidine [1, 2]

“…In addition, our sample of 2 showed a much higher melting point than reported (154 versus 115 • C). The reported [5] 1 H NMR data for 2 (see Table 1, entry 1) are not compatible with a static molecular structure as depicted in Fig. 1.…”

“…A synthesis of the title compound 2 from N,N ,Ntriaminoguanidinium chloride (1, X = Cl) and acetone, followed by deprotonation of the initially formed new guanidinium salt, has been published by Zelenin et al [5]. In our hands, several modifications were necessary to obtain 2 in satisfactory yield and purity.…”

Recent Developments in the Ring‐Chain Tautomerism of 1,3‐Heterocycles

“…Either open or cyclic tautomeric forms of the acetophenone and propiophenone derivatives could be prepared, but no equilibrium was observed between these compounds (Scheme 27). [37] Scheme 27…”

Oxidant-induced intramolecular triazole formation

“…16 Since 1976, crystal structures of benzylidene-1,2,4-triazole derivatives have been reported by Werner et al [17][18][19][20] and Capy et al 21 20 years later, Zelenin et al described 5-endo (CvN + NH) cyclizations via ring-chain tautomerism of triamino-guanidinum salts, but came to the conclusion that the linear form was the predominant species. 22,23 In 2000, we reported the unexpected cyclization of the triamino-guanidinium based ligand 1 forming a 1,2,4-triazole unit in the crystal structures of a protein-seized doughnut shaped coordination oligomer. 24 Using 1 as a ligand for the synthesis of a Pd(II)-based coordination capsule with octahedral shape, a PdPPh 3 -triazole complex [Pd(PPh 3 )(H 2 L′)] 4 was observed as well.…”