Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

Abstract

Depending on the reaction conditions, N,N’,N’’-tris(benzylamino)guanidinium salts can react with carboxylic acid chlorides to form either symmetrical N,N’,N’’-tris(N-acyl-N-benzylamido)guanidines 6 or mesoionic 4-amino-1,2,4-triazolium-3-hydrazinides 7. The latter were converted into 1,2,4-triazolium salts by protonation or methylation at the hydrazinide nitrogen atom. Neutral 1,2,4-triazoles 10 were obtained by catalytic hydrogenation of an N-benzyl derivative. Crystal structure analyses of a 4-benzylamino-1,2,4-triazolium-3-hydrazinide and of two derived 1,2,4-triazolium salts are presented.

Derivatives of the triaminoguanidinium ion, 6. Aminal-forming reactions with aldehydes and ketones

“…Thus, 3-Cl was found to undergo threefold N-carbamoylation with various arylisocyanates and thiocarbamoylation (leading to thiourea derivatives) with arylisothiocyanates [10]. In a similar manner, triple N-acylation with acid chlorides produced N,N′,N″-tris(Nacyl-N-benzylamino)guanidines, which under the action of aqueous NaOH could be transformed into mesoionic 1,2,4-triazolium-3-aminides [11]. Reactions of salts 3 with aldehydes or ketones have not been reported so far.…”

“…N,N′,N″-Triaminoguanidinium salts 1 (Fig. 1) are readily accessible, simple building blocks for organic synthesis, which due to their C 3 -symmetric topology and functional group presence offer diverse opportunities for the preparation of other ionic or neutral guanidine derivatives and of nitrogen heterocycles [1,2]. By reaction with aldehydes or ketones, the three NH 2 groups in 1 allow the straightforward conversion into tris(imines) (or (tris(hydrazones)) 2 [2][3][4][5][6], some of which were employed as ligands with multiple coordination sites in transition metal complexes showing remarkable three-dimensional architectures [2,5,7,8].…”