Triazoles. XIV—¹⁵N NMR study of substituted 5‐amino‐1,2,4‐triazoles

Abstract

15N NMR chemical shifts were measured for a series of substituted 5‐amino‐1,2,4‐triazoles. The assignment of isomeric structures agrees with earlier results obtained with the use of proton‐coupled 13C NMR.

On triazoles XLVIII. Synthesis of isomeric amino‐thiazolo‐[1,2,4]triazole, amino‐[1,2,4]triazolo‐[1,3]thiazine and ‐[1,3]thiazepine derivatives

“…The chemical shift of the NH 2 groups appearing at δ = 6.1, 6.0, 6.0 and 6.05 ppm, respectively, even not excluding the 4H tautomeric structure points rather to their 1H dominant tautomeric structure in agreement with the previous results obtained with the 5-amino-3-alkylthio-1,2,4-triazoles [21] (Scheme 6) and corroborated also by 15 N-nmr [22]. respectively.…”

On triazoles XLIX. Synthesis of 5,6‐dihydrothiazolo[3,2‐b]‐[1,2,4]triazol‐2‐yl‐, 6,7‐dihydro‐5H‐[1,2,4]triazolo[5,1‐b][1,3]thiazin‐2‐yl‐, and 5,6,7,8‐tetrahydro[1,2,4]triazolo[5,1‐b] [1,3]thiazepin‐2‐yl‐isoquinolinium salts

“…A preparative proof for structure 6 of the products obtained showed that S-alkylation reactions of 6 give products of type 1 identical with those obtained previously [2] by the ring closure of the S-alkyl triazoles (4) with the corresponding ortho-acyl phenylacetones (2) (Scheme 3, Tables II and IIa).…”

“…To corroborate the above idea a 6b type N-benzyl derivative 9 was synthesised as a model compound by structure proving synthesis starting from the corresponding 2 (R = 4-chlorophenyl, R 1 , R 2 = methoxy) and 3-amino-4-benzyl-4,5-dihydro-1H-1,2,4-triazole-5-thione (8) [4] (Scheme 5). The carbon atom 5' of derivative 9 was shifted downfield to 169.1 ppm as compared with those of derivatives 6 appearing at 159.3-162.9 ppm pointing out its 5'thione structure.…”

“…The reaction of compounds 6 with dibromomethane (10) led to dimeric derivatives (11) (Scheme 6) as proved by their mass spectra and Table I Synthetical Data of N- (5'-mercapto-1'H-1,2,4-triazol-3'-yl) the analogy of the chemical shifts of the triazole carbon atoms 3' and 5' with those of the alkylthio derivatives 1 (Schemes 3 and 6). Performing the reaction with 1,2-dibromoethane (12), 1,3dibromopropane (13) and 1,4-dibromobutane (14) new type 5,6-dihydro-thiazolo [3,2-b] [1,2,4]triazol-2-yl-isoquinolinium salts (15), 6,7-dihydro-5H- [1,2,4]triazolo [5,1-b] [1,3]thiazin-2-yl-isoquinolinium salts (16) and 5,6,7,8-tetrahydro [1,2,4]triazolo [5,1-b] [1,3]thiazepin-2-yl-isoquinolinium salts (17), respectively, were obtained (Scheme 7).…”

“…Structures 15-17 were also proved through a preparative method, by the reactions of derivatives 2 with the corresponding 2-amino-5,6-dihydrothiazolo [3,2-b] [1,2,4]triazole (24), 2-amino-6,7-dihydro-5H- [1,2,4]triazolo [5,1-b]- [1,3]thiazine (25) and 2-amino-5,6,7,8-tetrahydro[1,2,4]triazolo [5,1-b] [1,3]thiazepine (26), respectively (Scheme 10), which were recently prepared by us [1]. EXPERIMENTAL Melting points were determined on a Kofler-Boëtius micro apparatus and are not corrected.…”