A combined experimental and theoretical study of the alkylation of 3,5‐dithioxo‐[1,2,4]triazepines |
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| Authors: | M. Esseffar M. El Messaoudi R. Jalal L. R. Domingo M. J. Aurell |
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| Affiliation: | 1. Département de Chimie Faculté des Sciences Semlalia, Université Cadi Ayyad, BP 2390 Marrakesh, Morocco;2. Département des Sciences Chimiques, Faculté des Sciences et Techniques, Université Cadi Ayyad, BP 549 Marrakesh, Morocco;3. Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain |
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| Abstract: | The chemo‐ and regioselective alkylation reactions of 3,5‐dithioxo[1,2,4]triazepine 1 in a basic medium with α,ω‐dibromoalkanes 2a – c , Br(CH2)nBr (n = 1–3), are studied experimentally and theoretically. These alkylations, which occur at the thioxo sulfur atom in position 5, afford mainly 5‐bromomethylthio‐2,7‐dimethyl‐ 2,3‐dihydro‐ 4H[1,2,4]triazepin‐3‐one 3 for n = 1, 6,8‐dimethyl‐5‐thioxo‐2,3,4,5‐tetrahydro‐6H[1,3]thiazolo[4,5‐d][1,2,4]triazepine 4 for n = 2 and 7,9‐dimethyl‐6‐thioxo‐2,3,4,5,6,7‐hexahydro[1,3]thiazino [4,5‐d][1,2,4]triazepine 5 for n = 3. Theoretical calculations have been carried out at the B3LYP/6‐31G* and B3LYP(benzene)/6‐311+G*//B3LYP/6‐31G* levels, in order to rationalize the experimental observations. Both chemo‐ and regio‐selectivities of the alkylation reactions are analyzed. Copyright © 2008 John Wiley & Sons, Ltd. |
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| Keywords: | triazepines alkylation SN2 mechanism transition structures DFT calculations |
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