Mechanism of the cyclization of dimethyl diethynyl silane with selenium tetrabromide: Computational and structural studies, and monitoring
作者:Svetlana V. Amosova、Vladimir A. Shagun、Alexander V. Martynov、Natalia A. Makhaeva、Lyudmila I. Larina、Konstantin A. Lysenko、Mikhail G. Voronkov
DOI:10.1016/j.jorganchem.2007.01.023
日期:2007.7
The structure of 2,4-dibromo-2-dibromomethyl-3,3-dintethyl-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 Br-2... 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 H-1 NMR method. (c) 2007 Elsevier B.V. All rights reserved.