Visible-light mediated regioselective approach towards synthesis of 7-aroyl-6-methyl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines |
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Authors: | Ranjana Aggarwal Shilpa Sharma Mona Hooda Dionisia Sanz Rosa M Claramunt Brendan Twamley Isabel Rozas |
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Institution: | 1. Department of Chemistry, Kurukshetra University, Kurukshetra, 136119, Haryana, India;2. Departamento de Química Orgánica y Bio-orgánica, Facultad de Ciencias, UNED, Senda del Rey 9, E-28040, Madrid, Spain;3. School of Chemistry, Trinity College, Dublin, Dublin 2, Ireland;4. School of Chemistry, Trinity Biomedical Sciences Institute, Trinity College, Dublin, Dublin 2, Ireland |
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Abstract: | The first visible-light mediated, simple, efficient and ecofriendly protocol for the regioselective synthesis of novel 1,2,4]triazolo3,4-b]1,3,4]thiadiazines has been developed by the reaction of α-bromodiketones, generated in situ by the bromination of a diverse array of β-diketones with N-bromosuccinimide, with 4-amino-1,2,4]triazole-3-thiols. The methodology does not require the presence of any additives and this reaction proceeded in the presence of EDG (OMe), EWG (Cl) and heteroarenes (thiophenyl) giving the expected products in good to excellent yields. A solvent free protocol was also established to accomplish the synthesis of target compounds but it required PTSA as a catalyst and yields are comparatively poor. The structure of the regioisomer has been confirmed unambiguously by heteronuclear 2D-NMR (1H-13C) HMBC, (1H-15N) HMBC, (1H-13C) HMQC] spectroscopic and X-ray crystallographic studies. |
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Keywords: | Corresponding author Visible-light Regioselective synthesis Unsymmetrical diketones 4-Amino-[1 2 4]triazole-3-thiols Heteronuclear 2D NMR |
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