Mechanism of the cyclization of dimethyl diethynyl silane with selenium tetrabromide: Computational and structural studies, and monitoring |
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| Authors: | Svetlana V Amosova Vladimir A Shagun Natalia A Makhaeva Konstantin A Lysenko |
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| Institution: | a A.E. Favorsky Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, 1, Favorsky 664033, Russia
b A.N. Nesmeyanov Institute of Organoelement Compounds of RAS, Moscow, 28, Vavilov Str. 119991, Russia |
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| Abstract: | The structure of 2,4-dibromo-2-dibromomethyl-3,3-dimethyl-1-selena-3-silacyclopentene-4, formed by regioselective electrophilic addition of SeBr4 to dimethyl diethynyl silane, has been determined using X-ray analysis technique. Quantum chemistry methods were used to study elementary stages of the reaction. It was found that the first stage consisted of SeBr4 conversion into bimolecular complex Br2?SeBr2, initiated by dimethyl diethynyl silane. Possible formation of five-membered and six-membered heterocycles involves different cyclization mechanisms. The formation of only five-membered heterocycle is explained by kinetically preferable ring closure through four-center transition state. The conclusions obtained by calculations were confirmed by monitoring of the reaction using 1H NMR method. |
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| Keywords: | Chalcogens Five-membered unsaturated heterocycles Reaction mechanisms NMR spectroscopy X-ray diffraction |
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