Syntheses and investigations of electron acceptor substituted barbaralanes.
Item
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Title
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Syntheses and investigations of electron acceptor substituted barbaralanes.
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Identifier
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AAI9325165
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identifier
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9325165
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Creator
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Win, War War.
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Contributor
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Adviser: Klaus G. 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 degenerate Cope rearrangement in homotropilidene I{dollar}\sp1,{dollar} the fundamental work of Doering and Roth, is one of the interesting chapters of organic chemistry.;This project will focus on our attempts to reduce the activation energies for the Cope rearrangements of barbaralane II and semibullvalene III{dollar}\sp2,{dollar} which have the essential structure element of the homotropilidene system I. The activation energies of the Cope rearrangement of compounds II and III are 7.6 kcal/mol and 5.4 kcal/mol respectively. Theory has predicted that the activation energy of the Cope rearrangement of compound III would be lowered by substituting electron acceptors at C{dollar}\sb2,{dollar} C{dollar}\sb4,{dollar} C{dollar}\sb6{dollar} and C{dollar}\sb8{dollar} positions. Furthermore, Hoffmann and Stohrer reported that four cyano groups at C{dollar}\sb2,{dollar} C{dollar}\sb4,{dollar} C{dollar}\sb6{dollar} and C{dollar}\sb8{dollar} positions would lower the activation energy of compounds II and III by 9.6 kcal/mol, making the 2,4,6,8-tetracyanobarbaralane IV{dollar}\sp3{dollar} an important target molecule. As the direct access to compound IV is difficult, we have investigated other pathways toward IV via 2,4,6,8-tetracarbomethoxy-barbaralane V{dollar}\sp4.{dollar}.;A new synthetic approach toward electron acceptor substituted barbaralanes has been described in this thesis{dollar}\sp5.{dollar} Strong equilibrium preferences are observed for compounds VI, VIII, IX and XIII with the equilibrium on the site of the most electron acceptor substituents on the double bond. Lowering of the activation energy of the Cope rearrangement is observed for the dynamic barbaralanes V, X, XI, XII and XIV. The dynamic behavior of compounds V, X and XII, as determined by variable temperature X-ray, NMR and IR spectroscopy, has been studied. ftn{dollar}\sp1{dollar}See Figure 2 (p. 2), in dissertation for illustration. sk10{dollar}\sp2{dollar}See Table 2 (p. 5), in dissertation for illustration. sk10{dollar}\sp3{dollar}See structure #19 of Figure 21 (p. 22), in dissertation for illustration. sk10{dollar}\sp4{dollar}See Figure 131 (p. 185), in dissertation for illustration. sk10{dollar}\sp5{dollar}See footnote #4.
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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.
