The objective of this study was to explore intramolecular ketene cycloadditions with the anticipated results of developing new synthetic methodology for the synthesis of polycyclic compounds difficult to obtain by other procedures. (o-Alkenylphenoxy)ketenes were initially selected for this study because these ketenes provided a favorable proximity for the intramolecular [2+2] cycloaddition reactions. The difunctional precursors, (o-alkenylphenoxy)- acetic acids, were readily prepared from o-alkenylphenols and ∝-halocarboxylic acids and were converted to the corresponding acid chlorides by reaction with oxalyl chloride. The acid chlorides were dehydrochlorinated to the corresponding (o-alkenylphenoxy)ketenes by treatment with triethylamine. The ketenes undergo a facile intramolecular [2+2] cycloaddition to give polycyclic eye 1obutanones. The (o-vinylphenoxy)ketenes are clearly more reactive than the (o-allylphenoxy)ketenes and provide much better yields of the cycloaddition products because of electronic effects in the transition state in the cycloaddition process. The intramolecular [2+2] cycloadditions of keteniminium salts were included in this study as a more electrophilic alternative to ketenes that will react with less nucleophilic carbon-carbon double bonds. However, the use of keteniminium salts instead of ketenes in Intramolecular cycloadditions does have some limitations. The synthesis of benzofurans via the intramolecular [2+2] cycloadditions of (o-acylphenoxy)ketenes was accomplished. The initially formed ß-lactone cycloaddition products spontaneously underwent decarboxylation to the benzofurans. The aromaticity of the benzofurans is apparently a very strong driving force for the cycloaddition. During the course of this study, two new synthetic methods were discovered which in many instances represent a significant Improvement over existing methods. The Wittig Reactions of ketoacids without protecting the carboxyl groups provide a reliable source of the precursor unsaturated acids needed for intramolecular ketene-olefin cycloadditions. Also, the one-pot preparation of intramolecular ketene cycloaddition products from the carboxylic acid via the tosylate represents a new synthetic method. This procedure eliminates the acid halide preparation, isolation and purification step, thereby significantly simplifying the synthesis.

This study deals with the (4+2)-cycloaddition reactions of 4-π electron compounds with ketenes. Chloroketenes were generated in situ from the corresponding chlorinated acid chlorides in the presence of the ketenophiles. Chloro-, dichloro- and diphenylketenes reacted with 1-methoxy-3-trimethylsiloxy-l,3-butadiene, and 2,4-bis(trimethylsiloxy)-1,3-pentadiene to yield the corresponding dihydropyrans. The dihydropyrans yielded substituted 4-pyranones on hydrolysis.

A 5-membered INOC cycloadduct 84 was employed to prepare alcohol 91, which was transformed into several cyclopent-2-enone derivatives 94-96. / By using intramolecular nitrile oxide-alkene cycloaddition (INOC) as the kep step to construct hydroxylated carbocycles, gabosine F was synthesized for the first time from L-arabinose. Hence, theoretically, gabosine B, which is the enantiomer of gabosine F, can also be synthesized from D-arabinose by the same synthetic strategy. / In this thesis, the background information on the construction of carbocycles from carbohydrates via intramolecular 1,3-dipolar cycloaddition is presented. A review regarding the syntheses of gabosine B and cocaine are also descibed. / Starting with D-ribose, INAC of nitrones 113, 129, and 140, bearing an alpha/beta-unsaturated ester as the dipolarophile was studied. The INAC endo-cycloadduct 141 (cycloheptane) was converted into natural cocaine sucessfully, together with cocaine analogues 162,169,170,173,175, and 177. / The regioselectivity of intramolecular nitrone-alkene cycloaddition (INAC) was studied. The INAC of hept-6-enose nitrone 98, with a 3,4- trans-pentylidene acetal as the only blocking group, afforded endo-cycloadduct 97 (cycloheptane) exclusively. This result concluded that the regiospecific outcome of this INAC reaction is due to the present of the 3,4-trans-pentylidene acetal blocking group. / To investigate the regioselectivity in INAC of hex-5-enose with a 2,3- trans-pentylidene acetal blocking group, nitrones 178 and 195 were prepared from D-mannitol. endo-Cycloadducts (cyclohexanes) were afforded exclusively. / So, King Ho. / Adviser: Kung Ming Tony Shing. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 165-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

by Ching-hung Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 75-78). / Chapter i --- Biography / Chapter ii --- Abstract / Chapter iii --- Acknowledgments / Chapter iv --- Abberivations / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Review on the published syntheses of Zoapatanol --- p.1 / Chapter 1.2 --- Review on the construction of the oxepane ring --- p.7 / Chapter 1.3 --- "Review on the intramolecular nitrone and nitrile oxide 1,3-dipolar cycloaddition" --- p.15 / Chapter 1.3.a. --- Nitrone-olefin cycloaddition --- p.16 / Chapter 1.3.b. --- Nitrile-oxide-olefin cycloaddition --- p.17 / Chapter 1.4 --- Isoxazoline Transformation --- p.18 / Chapter Chapter 2 --- Results and Discussion / Chapter 2.1 --- General Aspect --- p.19 / Chapter 2.2 --- "Entries to 6 and 7-membered O-heterocycles via 1,3-dipolar nitrone cycloaddition" --- p.21 / Chapter 2.3 --- "Entries to 6 and 7-membered O-heterocycles via l,，3-diploar nitrile oxide cycloaddition" --- p.33 / Chapter 2.4 --- Conclusion --- p.47 / Chapter Chapter 3 --- Experimental / General --- p.49 / Experimental --- p.51 / References --- p.75

Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemistry. / Vita. / Bibliography: leaves [95]-99. / by Stephen Koch. / Ph.D.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Chemistry. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / Ph.D.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xiv, 240 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 95-104).