Degree Type

Dissertation

Date of Award

1984

Degree Name

Doctor of Philosophy

Department

Chemistry

Abstract

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-silatricyclo3.3.0.0-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.

DOI

https://doi.org/10.31274/rtd-180813-5666

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Michael J. Vuper

Language

en

Proquest ID

AAI8423683

File Format

application/pdf

File Size

125 pages

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