Date of Award
Doctor of Philosophy
Co-pyrolysis of 4-trimethylsilyl-1-methoxy-1-methyl-1-silacyclohexa-2,5-diene with MeOH afforded 1-methyl-1-methoxy-1-silacyclohexa-2,4-diene. Co-pyrolysis with acetylene afforded 1-methyl-1-silabicyclo2.2.2-octa-2,5,7-triene. Flash vacuum pyrolysis (FVP) gave a 4 + 2 Diels-Alder dimer of 1-methyl-1-silabenzene. These results are explained by a 1,3-trimethyl silyl shift followed by (beta)-elimination of Me(,3)SiOMe to form 1-methyl-1-silabenzene. This 1,3 shift was followed by NMR analysis of a static thermolysis of the silabenzene precursor;The photochemistry of 1-methyl-1-silabicyclo2.2.2-octa-2,5,7-triene (1-silabarrelene) was investigated. 1-Silabarrelene was found to quantitatively rearrange to 1-methyl-1-silatricyclo220.127.116.11-octa-2,6-diene (1-silasemibullvalene). 1-Silasemibullvalene did not undergo a Cope rearrangement as did the all-carbon system;The synthesis of a functionalized silacycloheptatriene was attempted via an intramolecular addition - rearrangement sequence involving methyl(2-propenyl)cyclopropylsilylene. The flash vacuum pyrolysis of the silylene precursor gave exceptionally complex mixtures whose major components were isomers of the starting material. Synthesis of 4-trimethylsilyl-1-methyl-1-methoxy-1-silabicyclo4.1.0hept-2-ene was carried out with the idea that it too would undergo a silyl migration and elimination of Me(,3)SiOMe to form a silanorcaradiene which would rearrange to a silacycloheptatriene. Pyrolysis of this material gave complex mixtures which were mainly isomers of the starting material;Silanaphthalene generation via (beta)-elimination of Me(,3)SiOMe was attempted, but the appropriate precursors could not be synthesized. FVP of (o-trimethylsilyl)phenylactylene produced an unusual product, 1,1-dimethyl-1-sila-2,3-benzocyclohexa-2,4-diene. Formation of this product was rationalized by insertion of an alkylidene carbene (from 1,2 shift of the acetylenic hydrogen) into a C-H bond of the o-trimethylsilyl group. Diazo transfer reaction on the anion of this silacyclohexadiene gave back unreacted starting material and the 2- and 4-diazosilacyclohexadienes. FVP of this mixture gave no evidence of a silanaphthalene.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Michael J. Vuper
Vuper, Michael J., "The synthesis of carbacyclic silanes via organosilicon reactive intermediates " (1984). Retrospective Theses and Dissertations. 7737.