Cyanic Acid Esters. 31. Reactions of 2‐Guanidino‐benzimidazole with Electrophilic Compounds

Synthesis and biological activity of fluorinated 2-amino-4-aryl-3,4-dihydro[1,3,5]triazino[1,2-a]benzimidazoles

“…The assignment of 1 H and 13 C NMR signals was made based on the data for analogous compounds [1,16,20] and the electronic effect of the substituents. The formation of the striazine ring in the reaction was suggested by the NMR spectral data ( Table 1).…”

“…To date only a limited number of studies on the synthesis of the above mentioned 2-amino-3,4-dihydro [1,3,5]triazino [1,2-a]benzimidazoles have been reported [1,2,16,17]. Fluorinated compound 3c has been reported to be synthesized; however no spectral data and elemental analysis results were presented in the article [2].…”

Three-component condensation of 4-aryl-1,4-dihydro-benzo[4,5]imidazo[1,2-a][1,3,5]triazin-2-amines with formaldehyde and primary amines

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Three-component cyclization of 4-aryl-1,4-dihydrobenzo [4,5]imidazo[1,2-a][1,3,5]triazin-2-amines with formaldehyde and primary amines gave the corresponding 6-unsubstituted or 6-aryl-2-alkyl-2,3,4,6-tetrahydro-1H- [1,3,5]triazino[1′,2′:3,4][1,3,5]triazino[1,2-a]benzimidazoles.III, VII, Ar = Ph (a), 4-MeOC 6 H 4 (b), 2,5-(MeO) 2 C 6 H 3 (c), 4-FC 6 H 4 (d); VI, VII, R = PhCH 2 (a), puridin-3-ylmethyl (b), 2-morpholinoethyl (c), PhCH 2 CH 2 (d).Reactions of substituted guanidines [1] and 2-aminobenzimidazoles [2] with formaldehyde and primary amines provide a synthetic route to hydrogenated 1,3,5-triazine derivatives. In the present work we performed analogous reaction with 4-aryl-1,4-dihydrobenzo [4,5]imidazo[1,2-a][1,3,5]triazin-2-amines IIIa-IIIf which are readily available via condensation of 1-(1H-benzimidazol-2-yl)guanidine (I) with aromatic aldehydes IIa-IIf (Scheme 1).

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“…Three-component cyclization of 4-aryl-1,4-dihydrobenzo [4,5]imidazo[1,2-a][1,3,5]triazin-2-amines with formaldehyde and primary amines gave the corresponding 6-unsubstituted or 6-aryl-2-alkyl-2,3,4,6-tetrahydro-1H- [1,3,5]triazino[1′,2′:3,4][1,3,5]triazino[1,2-a]benzimidazoles.…”

“…In the present work we performed analogous reaction with 4-aryl-1,4-dihydrobenzo [4,5]imidazo[1,2-a][1,3,5]triazin-2-amines IIIa-IIIf which are readily available via condensation of 1-(1H-benzimidazol-2-yl)guanidine (I) with aromatic aldehydes IIa-IIf (Scheme 1). Martin et al [3] previously proposed two procedures for the synthesis of these compounds, and the products were assigned the structure of tautomeric 4-aryl-3,4-dihydrobenzo- [4,5]imidazo[1,2-a][1,3,5]triazin-2-amines IVa-IVf on the basis of only IR spectra and elemental analyses. We examined their 1 H NMR spectra in DMSO-d 6 and found that the CH and NH proton signals appear as two singlets, which corresponds to tautomeric structure of 4-aryl-1,4-dihydrobenzo [4,5]imidazo[1,2-a][1,3,5]-triazin-2-amines III, whereas the CH and NH protons in the triazine ring of tautomers IV should resonate as two doublets.…”