An unexpected tautomer: synthesis and crystal structure of N-[6-amino-4-(methylsulfanyl)-1,2-dihydro-1,3,5-triazin-2-ylidene]benzenesulfonamide
Reham A. Mohamed-Ezzat,
Galal H. Elgemeie,
Peter G. Jones
Abstract:The title compound, C10H11N5O2S2, consists of an unexpected tautomer with a protonated nitrogen atom in the triazine ring and a formal exocyclic double bond C=N to the sulfonamide moiety. The ring angles at the unsubstituted nitrogen atoms are narrow, at 115.57 (12) and 115.19 (12)°, respectively, whereas the angle at the carbon atom between these N atoms is very wide, 127.97 (13)°. The interplanar angle between the two rings is 79.56 (5)°. The molecules are linked by three classical hydrogen bonds, forming a … Show more
“…The structure of the compound is confirmed via single X-ray diffraction analysis as depicted in Fig. 2 [ 60 ]. Scheme 1.…”
Section: Resultsmentioning
confidence: 99%
“…2 The molecule of Structure 3a in the crystal. “The figure is reproduced via permission of the International Union of Crystallography under the open-access licence” [ 60 ] …”
Novel approach for synthesizing triazine sulfonamide derivatives is accomplished via reacting the sulfaguanidine derivatives with N-cyanodithioiminocarbonate. Further reaction of the novel triazine sulfonamide analogues with various secondary amines and anilines generated various substituted triazine sulfonamide analogues of promising broad-spectrum activities including anti-microbial, anti-tumor, and anti-viral properties. The in vitro anti-proliferative activities of most of the novel compounds were evaluated on the NCI-60 cell line panel. The antifungal and antibacterial activities of the compounds were also estimated. The anti-viral activity against SARS CoV-2 virus was performed using MTT cytotoxicity assay to evaluate the half-maximal cytotoxic concentration (CC50) and inhibitory concentration 50 (IC50) of a representative compound from the novel triazine sulfonamide category. Compound 3a demonstrated potent antiviral activity against SARS-CoV-2 with IC50 = 2.378 µM as compared to the activity of the antiviral drug remdesivir (IC50 = 10.11 µM). Our results indicate that, upon optimization, these new triazine sulfonamides could potentially serve as novel antiviral drugs.
“…The structure of the compound is confirmed via single X-ray diffraction analysis as depicted in Fig. 2 [ 60 ]. Scheme 1.…”
Section: Resultsmentioning
confidence: 99%
“…2 The molecule of Structure 3a in the crystal. “The figure is reproduced via permission of the International Union of Crystallography under the open-access licence” [ 60 ] …”
Novel approach for synthesizing triazine sulfonamide derivatives is accomplished via reacting the sulfaguanidine derivatives with N-cyanodithioiminocarbonate. Further reaction of the novel triazine sulfonamide analogues with various secondary amines and anilines generated various substituted triazine sulfonamide analogues of promising broad-spectrum activities including anti-microbial, anti-tumor, and anti-viral properties. The in vitro anti-proliferative activities of most of the novel compounds were evaluated on the NCI-60 cell line panel. The antifungal and antibacterial activities of the compounds were also estimated. The anti-viral activity against SARS CoV-2 virus was performed using MTT cytotoxicity assay to evaluate the half-maximal cytotoxic concentration (CC50) and inhibitory concentration 50 (IC50) of a representative compound from the novel triazine sulfonamide category. Compound 3a demonstrated potent antiviral activity against SARS-CoV-2 with IC50 = 2.378 µM as compared to the activity of the antiviral drug remdesivir (IC50 = 10.11 µM). Our results indicate that, upon optimization, these new triazine sulfonamides could potentially serve as novel antiviral drugs.
The compounds 2′,3′,4′,6′-tetra-O-acetyl-β-D-glucopyranosyl N′-cyano-N-phenylcarbamimidothioate (C22H25N3O9S, 5a), 2′,3′,4′,6′-tetra-O-acetyl-β-D-galactopyranosyl N′-cyano-N-phenylcarbamimidothioate, (C22H25N3O9S, 5b), 2′,3′,4′,6′-tetra-O-acetyl-β-D-galactopyranosyl N′-cyano-N-methylcarbamimidothioate (C17H23N3O9S, 5c), and 2′,3′,4′,6′-tetra-O-acetyl-β-D-galactopyranosyl N′-cyano-N-p-tolylcarbamimidothioate (C23H27N3O9S, 5d) all crystallize in P212121 with Z = 4. For all four structures, the configuration across the central (formal) C=N(CN) double bond of the carbamimidothioate group is Z. The torsion angles C5—O1—C1—S (standard sugar numbering) are all close to 180°, confirming the β position of the substituent. Compound 5b involves an intramolecular hydrogen bond N—H...O1; in 5c this contact is the weaker branch of a three-centre interaction, whereas in 5a and 5d the H...O distances are much longer and do not represent significant interactions. The C—N bond lengths at the central carbon atom of the carbamimidothioate group are almost equal. All C—O—C=O torsion angles of the acetyl groups correspond to a synperiplanar geometry, but otherwise all four molecules display a high degree of conformational flexibility, with many widely differing torsion angles for equivalent groups. In the crystal packing, 5a, 5c and 5d form layer structures involving the classical hydrogen bond N—H...Ncyano and a variety of ‘weak’ hydrogen bonds C—H...O or C—H...S. The packing of 5b is almost featureless and involves a large number of borderline ‘weak’ hydrogen bonds. In an appendix, a potted history of wavelength preferences for structure determination is presented and it is recommended that, even for small organic crystals in non-centrosymmetric space groups, the use of Mo radiation should be considered.
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