Synthesis and investigations of substituted semibullvalenes.
Item
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Title
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Synthesis and investigations of substituted semibullvalenes.
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Identifier
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AAI9325082
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identifier
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9325082
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Creator
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Connelly, Mercedes B.
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Contributor
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Adviser: Klaus Grohmann
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Date
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1993
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic
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Abstract
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The concept of homoaromaticity, introduced into organic chemistry by Saul Winstein in 1959,{dollar}\sp1{dollar} has stimulated and intrigued many chemists over the last three decades. Homoaromaticity is a term used to describe systems in which the {dollar}\sigma{dollar} backbone of an aromatic species is interrupted by a saturated center and in which the geometry continues to favor overlap of the {dollar}\pi{dollar} system.;1,5-Dimethyl-2,4,6,8-tetracarbomethoxysemibullvalene{dollar}\sp2{dollar} 1,{dollar}\sp3{dollar} undergoes the fastest Cope rearrangement known to date. This prompted us to investigate semibullvalenes further. The main premise of our work is to further lower the energy of activation for the Cope rearrangement in semibullvalene, thus reaching a "transition state" of lower energy than the "ground state". It has been the goal of this thesis project to synthesize the first neutral bis-homoaromatic molecule. Both planar 1,5-annulated, such as 2 and 3, as well as non-annulated systems will be discussed.;A method was developed for the synthesis of 2,6-dicarbomethoxy-1,5-dimethylsemibullvalene 4 the resulting key intermediates 74 and 75 can be used as the starting material for the synthesis of differently substituted novel semibullvalenes. Solution state VT {dollar}\sp{13}{dollar}C NMR studies, ranging from room temperature down to 163K, indicate that 4 undergoes a very fast Cope rearrangement. ftn{dollar}\sp1{dollar}Winstein, S., J. Chem. Soc., 1959, 81, 6524.; Chem. Soc. Special Publication, 1967, No. 21, 5. sk10{dollar}\sp2{dollar}See page v of dissertation for figures. sk10{dollar}\sp3{dollar}Miller, L., Ph.D. Thesis, CUNY, 1982.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
