Date of Award
Doctor of Philosophy
The behavior of a variety of homoenolate anions generated either by hydrolysis of polycyclic ethers (homoketonization) or by base-catalyzed hydrogen abstraction from polycyclic ketones (homoenolization) has been investigated.;A series of polycyclic derivatives of cyclopropanol were prepared and the base-catalyzed ketonization of the corresponding cyclopropoxides was examined to establish the regio- and stereochemistry of the ring cleavage. The examples derived from 2.2.1 and 2.2.2 ketones, by Simmons-Smith cyclopropanation of their silyl enol ethers, were found to undergo ring expansion preferentially while less-strained analogs gave the (alpha)-methyl derivatives of the initial ketone. In all cases of ring expansion, the cleavage proceeds with high stereoselectivity favoring inversion of configuration upon protonation (deuteration).;A novel means of generating the 2-trimethylsilyl ethers of substituted homoquadricyclenes was discovered. Base-catalyzed ketonization of these derivatives was found to yield either the tricyclo 188.8.131.52('2,7) or 184.108.40.206('2,8) octanone skeletons depending upon the substitution at the 8-position of the starting material.;The Simmons-Smith reaction with t-butyldimethylsilyl enol ether of some polycyclic ketones under concentrated conditions led to cyclopropanation and isomerization to furnish the ring expanded allylic silyl ethers.;The behavior of the 7,7-dimethyltricyclo 220.127.116.11('2,7) nonan-6-ones under strongly basic conditions was examined to determine the effect of the three-membered ring for comparison with earlier findings for the 18.104.22.168('2,4) analogs. While the endo isomer was found to be stable, the exo isomer readily rearranged to 8,8-dimethyltricyclo 22.214.171.124('2,4) nonan-7-one. Experiments in t-BuOD were carried out to establish the several sites of deuterium incorporation in the initial ketones. These results clearly revealed that the three membered ring influences both the regio- and stereochemistry of (beta)-enolate formation. The observed differences for the exo and endo isomers of the 126.96.36.199('2,4) nonanones can be attributed to conformational differences.;Some support for this proposal was provided by the reactivities of endo-9,9-dimethyltricyclo 188.8.131.52('2,6) undecan-8-one, endo-3-t-butyl-3-methylbicyclo 3.2.1 octan-2-one and endo-9-t-butyl-9-methyltricyclo 184.108.40.206('2,6) undecan-8-one under strongly basic conditions.;Homoenolization of the 3,3-dimethyl-7-spirocyclopropyl and -7-isopropylidene derivatives of norcamphor provide efficient syntheses of the corresponding 3,3-dimethyl-5-substituted norcamphors. Hydrogenolysis of the 5-spirocyclopropyl derivative furnished the hitherto unknown 3,3,5,5-tetramethylcamphor.
Ragauskas, Arthur Jonas, "Synthetic And Mechanistic Features Of Base-catalyzed Homoenolization And Homoketonization" (1985). Digitized Theses. 1464.