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DOI: 10.1055/s-0035-1561848
Facile Access to 3,7-Dialkyltetrahydro-1H,5H-[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-dithiones
Publication History
Received: 12 December 2015
Accepted after revision: 20 January 2016
Publication Date:
01 March 2016 (online)
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Abstract
A simple single-step methodology was developed to synthesize 3,7-dialkyltetrahydro-1H,5H-[1,2,4]triazolo[1,2-a][1,2,4]triazole-1,5-dithiones in improved yields by acid-catalyzed reaction of thiosemicarbazide and aliphatic aldehydes in anhydrous ethanol at reflux temperature. The products were obtained in good to excellent yields. A plausible mechanism involving two successive intramolecular heterocyclizations of thiosemicarbazone has also been proposed. The synthesized compounds were characterized by spectroscopic methods and confirmed by using X-ray crystallography. These C-2 symmetric hexaheteroatomic fused heterocycles are expected to have exceptional applications.
Supporting Information
- Supporting information for this article is available online at http://dx.doi.org/10.1055/s-0035-1561848.
- Supporting Information
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References and Notes
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- 18 Synthesis of 3,7-Dibutyltetrahydro(1,2,4)triazolo(1,2-a)(1,2,4)triazole-1,5-dithione (Table 1, 4d): To a stirred solution of thiosemicarbazide 1 (0.138 g, 1.0 mM) in absolute EtOH (25 mL), butanal (0.75 mL, 1.3 mM) along with 1–2 drops of concd sulfuric acid was added. The mixture was heated under reflux for 18 h. On completion (TLC monitoring), the reaction mixture was cooled to r.t., and the precipitate was filtered and recrystallized from EtOH to afford 4d as a white solid; mp 186 °C; yield: 89%; Rf 0.68 (PE–EtOAc, 7:3). IR (KBr): 3390 (N–H), 2962 (Me C–H stretch), 1220 (C=S) cm–1. 1H NMR (300 MHz, DMSO-d 6): δ = 10.64 (s, 2 H, NH), 5.62 (s, 1 H, SH), 6.01 (dt, J = 12.0, 0.6 Hz, 1 H, NCHN), 1.31–1.39 (m, 5 H, CH2), 1.57–1.65 (m, 4 H, CH2), 0.89 (t, J = 6.9 Hz, 3 H, Me). 13C NMR (75 MHz, DMSO-d 6): δ = 185.9 (C=S), 76.1 (C–N), 33.9, 26.4, 21.3, 14.4 (aliphatic C). Anal. Calcd for C12H22N4S2: C, 50.31; H, 7.74; N, 19.56; S, 22.39. Found: C, 50.29; H, 7.76; N, 19.55; S, 22.40. HRMS: m/z [M] calcd for C12H22N4S2: 286.13; found: 286.11.
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- 20 CCDC 1063612 contains the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
- 21 Sheldrick GM. Acta Crystallographica Section A 2008; 64: 112