Synthesis of spirocyclosiloxanes by flash vacuum pyrolysis of 2,7-dimethyl-2,3: 7,8-diepoxy-5-silaspiro[4.4]nonane and cyclosiloxanes |
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| Affiliation: | 1. Department of Chemistry, of Sciences, Ferdowsi University of Mashhad, Mashhad 91775-1436, Iran;2. School of Chemistry, Damghan University, Damghan 36716-41167, Iran;3. Department of Biosystems, Faculty of New Technologies Engineering, Shahid Beheshti University, Tehran 19839-4716, Iran;1. Department of Chemistry, University of North Texas, 1155 Union Circle Drive #305070, Denton, TX 76203, USA;2. Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, UK |
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| Abstract: | Flash vacuum pyrolysis (FVP) of 2,7-dimethyl-2,3 : 7,8-diepoxy-5-silaspiro[4.4]-nonane with cyclotetra- or cyclopenta-siloxanes (D4 or D5) leads to products which apparently result from transannular insertion of [OSiO] or an equivalent synthon inti SIO single bonds of D4 or D5: 2,4,6,8,10-pentasila-1,3,5,7,9,11-hexaoxaspiro[5.5]undecane (D2QD2) and 2,4,6,8,10,12-hexasila-1,3,5,7,9,11,13-heptaoxaspiro[5.7]tridecane (D3QD2) respectively. The scope of this reaction has been explored with substituted cyclotetrasiloxanes such as heptamethylcyclotetrasiloxane, vinylheptamethylcyclotetrasiloxane, phenylheptamethylcyclotetrasiloxane, and chloromethylheptamethylcyclotetrasiloxane. In all cases, substituted spirocyclosiloxane products (D2QDDx) were obtained. 29Si NMR has proved particularly useful for the assignment of structure of these spirocyclosiloxanes. |
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