Baldwin, John E. (1963) Part I: Mechanism of the thermal isomerization of 2-norbornene-5, 6-endo-dicarboxylic anhydride. Part II: The aldoketene dimer rearrangement. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-10052005-154306
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PART I The Diels-Alder adduct of cyclopentadiene and maleic anhydride, 2-norbornene-5,6-endo-dicarboxylic anhydride, may be rearranged thermally to its exo-isomer. This isomerization is known to occur in part through an internal mechanistic pathway. In order to study the mechanism of this rearrangement, an attempt was made to synthesize 2-norbornene-5,6-endo-dicarboxylic anhydride stereospecifically labeled with carbon-14 in one carboxyl group, rearrange this material under conditions favoring the internal pathway, and degrade the exo-anhydride in a stereospecific fashion, measuring the carbon-14 activities of each carbonyl group separately.
Three synthetic approaches to the stereo specifically labeled endo-anhydride, through the intermediates ethyl cis-[...]-cyanoacrylate, (-)-menthyl hydrogen maleate, and (-)-menthoxymalealdehydic acid, have not been successful. Rearrangement of the endo-anhydride in the presence of tetracyanoethylene gave exo-anhydride from the internal mechanism and 2,2,3,3-tetracyanonorborn-5-ene from the external process. Degradation of 2-norbornene-5,6-exo-dicarboxylic anhydride by hydrogenation and reaction with (-)-menthol gave two diasteromeric (-)-menthyl hydrogen 2,3-exo-norbornanedicarboxylates, whose absolute configurations were established by degradation of one to an optically active 2-exo-norbornanecarboxylic acid.
2,3-Endo-norbornanedicarboxylic anhydride was rearranged to its exo-isomer when heated to 250º for 18 hours.
The neutral phenylketene dimer has been synthesized, identified as 3-hydroxy-2,4-diphenyl-3-butenoic lactone, reduced to [...],[...]-diphenylbutyric acid, and rearranged with base to an acidic isomer, tentatively postulated to be 2,4-diphenylcyclobutanedione or 2,4-diphenylcyclobutenolone.
Structural assignments for neutral methylketene dimer, acidic methylketene dimer, 3,5-dimethyl-6-ethylpyronone, 3,5-diphenyl-4-hydroxy-6-benzylpyrone, and 3,5-dimethyl-4-hydroxy-6-ethylpyrone have been confirmed or corrected.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Chemistry and Chemical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1963|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||06 Oct 2005|
|Last Modified:||26 Dec 2012 03:04|
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