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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

New chemistry of donor-acceptor cyclopropanes

Yu, Ming, Pagenkopf, Brian L., January 2004 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Brian L. Pagenkopf. Vita. Includes bibliographical references.
12

Diaryl-substituted cyclopropenones

Brause, Allan Robert. January 1965 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 41.
13

u-vinylidene and n-1-cyclopropenyliron complexes : chemistry and synthesis via 1, 1-dichlorocyclopropanes /

Hanlon, David James, January 1985 (has links)
Thesis (Ph.D.)--University of Oklahoma, 1985. / Includes bibliographical references.
14

Metalation of cyclopropanes and the chemistry of binor-s /

Hantosi, Zsolt. January 1999 (has links)
Thesis (Ph. D.)--University of Chicago, Dept. of Chemistry. / Includes bibliographical references. Also available on the Internet.
15

Directed carbozincation reactions of cyclopropene derivatives

Tarwade, Vinod. January 2010 (has links)
Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: Joseph M. Fox, Dept. of Chemistry & Biochemistry. Includes bibliographical references.
16

Studies related to the thermal rearrangement of 1,2-Divinylcyclopropanes

Burmeister, Max Stewart January 1981 (has links)
The work in this thesis was undertaken in order to determine the kinetic factors responsible for the regioselectivity in enol ether formation in 2—vinylcyclopropyl cyclohexyl ketone systems. Conversion of commercially available 4-carbethoxy-3-methyl-2-cyclo-hexen-l-one (106) into 3,3-dimethylcyclohexanecarboxylic acid chloride (.105) was accomplished via a straightforward sequence of reactions. Treatment of (105) with lithium (phenylthio)(cis-2-vinylcyclopropyl)cuprate (33) afforded the ketone (101). Alternatively, reaction of (105) with a mixture of the cuprate reagent (33) and the isomeric reagent (34), followed by base-catalyzed equilibration of the resultant mixture of ketones, provided the ketone (103). Hydrogenation of c_is-2-vinylcyclopropyl cyclohexyl ketone (89) with diimide provided the ketone (104). Treatment of the ketone (101) with lithium diisopropylamide in tetrahydrofuran at -78°C, followed by trapping of the resultant mixture of enolate anions with tert-butyldimethylsilyl chloride, gave a mixture of the enol silyl ethers (120) and (121) , in a ratio of 12 : 88. Thermolysis of the latter mixture (160°C, neat) afforded a mixture of the annulated materials (122) and (123) (ratio ~14 : 86), which, upon acid hydrolysis under mild conditions, gave the cycloheptenone (127) and compound (123). The latter two substances could be separated by column chromatography. Subjection of the ketone (103) to a sequence of reactions similar to that described above (lithium diisopropylamide, tetrahydrofuran; tert-butyldimethylsilyl chloride; thermolysis, 240°C, neat; acid hydrolysis) gave the final products (127) and (123) in a ratio of 87 : 13, respectively. Treatment of cis-2-ethylcyclopropyl cyclohexyl ketone (104) with lithium diisopropylamide in tetrahydrofuran, followed by trapping of the resultant mixture of enolate anions with tert-butyldimethylsilyl chloride afforded the two enol silyl ethers (125) and (126) in a ratio of 1:1. The results summarized above are discussed in terms of the factors which might be affecting the regioselectivity of kinetic deprotonation of 2-vinylcyclopropyl cyclohexyl ketone systems. / Science, Faculty of / Chemistry, Department of / Graduate
17

Studies related to the preparation of 2-alkyl- and 2-alkenyl-1,3-cyclohexanediones ; An investigation into the regioselective formation of -IODO ,-unsaturated ketones from unsymmetrical 1,3-cyclohexanediones ; Studies related to the divinylcyclopropane rearrangement

Grierson, John Rodney January 1983 (has links)
The work described in this thesis is devoted to three separate synthetic methods studies, which represent some past and current interests in our laboratory. In the first study, a preparation of 2-alkyl- and 2-alkenyl-1,3-cyclohexanediones (2) from 1,5-dimethoxy-1,4-cyclohexadiene (14) is described. Metalation of the diene (14) with tert-butyllithium in tetrahydrofuran solution at low temperature (-78°C) followed by addition of an alkyl or alkenyl halide, in the presence of hexamethylphosphoramide, resulted in a completely regioselective alkylation reaction affording the corresponding 6-alkyl- or 6-alkenyl-1,5-dimethoxy-1,4-cyclohexadiene (16). The latter substances were isolated in good to excellent yields. Simple aqueous hydrolysis of these materials in the absence of air afforded the desired 2-alkyl- and 2-alkenyl-1,3-cyclohexanediones (2) in good yields. In the second study, an investigation into the regioselective formation of β-iodo α,β-unsaturated ketones (e.g., (64) and (65)) from unsym-metrical 1,3-cyclohexanediones (63) employing triphenylphosphine diiodide-triethylamine in acetonitrile is described. It has been found that when one of the carbonyl functionalities of the substrate is quite steric-ally hindered the reaction is nearly completely regioselective. In the third study, the thermal (Cope) rearrangement of the bicyclic dienes (136a), (136b-E), and (136b-2) and the tricyclic dienes (137a-d) is described. In each case, thermolysis of the substrate at 240°C followed by hydrolysis of the intermediate product thus obtained afforded a bicyclo-[3.2.2]non-6-en-3-one, ketones (148), (149), (150) and (151a-d), respectively, in fair to good overall yield (49-81%). / Science, Faculty of / Chemistry, Department of / Graduate
18

Cyclopropyl anion as an allyl anion synthon.

January 1990 (has links)
by Dennis K.P. Ng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 74-79. / ACKNOWLEDGEMENTS --- p.i / CONTENTS --- p.ii / LIST OF FIGURES --- p.iii / LIST OF TABLES --- p.iv / ABSTRACT --- p.v / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 2. --- RESULTS AND DISCUSSION / Chapter 2.1. --- Preparation of Dithioacetals --- p.20 / Chapter 2.2. --- Coupling Reaction of Cyclopropylmagnesium Bromide with Benzylic Dithioacetals --- p.20 / Chapter 2.3. --- "Coupling Reaction of Cyclopropylmagnesium Bromide with 2-Aryl-2-trimethylsilyl- 1,3-dithianes" --- p.29 / Chapter 2.4. --- Coupling Reaction of Substituted Cyclopropylmagnesium Bromides with Benzylic Dithioacetals --- p.36 / Chapter 2.5. --- Coupling Reaction of Cyclobutyl- and Cyclopentyl-magnesium Bromides with Benzylic Dithioacetals --- p.45 / Chapter 2.6. --- Conclusion --- p.48 / Chapter 3. --- EXPERIMENTAL SECTION / Chapter 3.1. --- General Directions --- p.49 / Chapter 3.2. --- Preparation of Dithioacetals --- p.50 / Chapter 3-3. --- Preparation of Substituted Cyclopropyl Bromides --- p.56 / Chapter 3.4. --- "Coupling Reaction of Cyclopropyl-, Cyclobutyl- and Cyclopentyl-magnesium Bromides with Benzylic Dithioacetals" --- p.60 / Chapter 3.5. --- "Coupling Reaction of Cyclopropylmagnesium Bromide with 2-Aryl-2-trimethylsilyl- 1,3-dithianes" --- p.65 / Chapter 3.6. --- Coupling Reaction of Substituted Cyclopropylmagnesium Bromides with Benzylic Dithioacetals --- p.67 / Chapter 3.7. --- Miscellaneous Syntheses --- p.71 / Chapter 4. --- REFERENCES AND NOTES --- p.74 / Chapter 5. --- APPENDIX --- p.80
19

Synthesis of enantiomeric [m][n]paracyclophanes.

January 1989 (has links)
Chi-wai Hung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 60-62.
20

Asymmetric synthesis of cyclopropanes via a "zipper reaction"

Lincoln, Christopher M. 07 March 2005 (has links)
The rearrangement of a homoallyl cation to a cyclopropylcarbinyl cation is thought to play a role in the biogenesis of a variety of cyclopropane-containing natural products,¹ a hypothesis which has previously led to the design of successful biomimetic syntheses of several natural products.² The strategy underlying this approach to cyclopropane synthesis³ can be applied more broadly and would be particularly valuable if it could be extended to a set of contiguous cyclopropanes. This concept has led us to examine the rearrangement of certain homoallylic systems bearing a leaving group (triflate) at one terminus and a cation-stabilizing metal (tin) at the other. The effects of protecting groups of varying steric demand and of olefin geometry on the stereochemical outcome of the cyclization were examined. "Zipper" cyclization of (8R,5E,2Z)-1-tri-n-butylstannyl-9-trityloxy-nona-2,5-dien-8-ol (117) led to the stereoselective formation of three distinct bicyclopropane stereoisomers (110,111,112). The major diastereomer was isolated through derivatization and the absolute stereochemistry was verified by X-ray crystallography. The trans,syn,trans-bicyclopropane 118 was carried forward to complete a formal synthesis of the antifungal agent FR-900848 (49). The synthesis of a key precursor to halicholactone (188), neohalicholactone (189), and the solandelactones A-H (190-197) constructed around a transcyclopropane core is also described. The key steps in this synthesis are the stereoselective synthesis of trans-vinylcyclopropane 79, followed by a highly diastereoselective acetate aldol reaction leading to compound 269. / Graduation date: 2005

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