No description available.

No description available.

This thesis describes two main programmes: the synthesis of a new class of homochiral amines and the synthesis of ketone analogues of 3a-esterified tropane alkaloids. In chapter one, a scaled-up synthesis of (5)-a-(diphenylmethyl)pyrrolidine 1 is described. The key hydrogenation step of the oxazolidinone intermediate 2 was extended to the synthesis of the other chiral amines 70, 73, 76, 79 and 82. Hydrogenation of the oxazolidinones proceeded in good yields (71 - 87 %) and was not susceptible to racemisation. Thus, a convenient route from amino acid ester hydrochlorides (S)-valine 65, (S)-phenylalanine 66, (S)-alanine 67, (S)-isoleucine 68 and (S)-leucine 69 allowed a range of novel chiral amines to be prepared. In chapters two and three, a new route to ketone analogues of tropane esters is described. In chapter two, results of an attempt to prepare ketone 110 are outlined. Ketone 110 is an analogue of the tropane alkaloid littorine 101, where the bridging ester O atom is replaced by a CH2 group. The first approach to ketone 110 involved the Wittig reaction of acetylmethylenephosphorane 118 and the Homer-Wadsworth- Emmons reaction of diethylbenzoylmethanephosphonate 122 with tropinone 116. Tropinone 116 was found to be particularly unreactive in both cases. The second approach to ketone 110 involved the coupling reactions of both N-troc-3a- tosyloxymethyltropane 170 and N-troc-3 a-iodomethyltropane 185 with 2-phenylacetyl- 1,3-dithiane 147 and 1,3-ditihiane 142. These were also unreactive and as a result the synthesis of ketone 110 remains unresolved. In chapter three, the synthesis of other ketone analogues of naturally occurring 3 a- esterified tropane alkaloids is described. A six-step route to the ketones was devised and in this route the Grignard reactions of tropan-3 -ylacetaldehyde 227 emerged as the key to the success of the strategy. Three ketone analogues 218, 219 and 220 of tropate esters were successfully prepared. Ketone 220, the analogue of apoatropine 201, was found to be a muscarinic acetylcholine receptor antagonist (EC(_50) 1.9x10(^-7) M) in guinea-pigileum, showing a 500-fold less activity than atropine 202. However the activity is still within the clinical range.

Call number: LD2668 .T4 1950 O2 / Master of Science

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Graduation date: 2003

The aim of our project is to build new catalysts for the asymmetric epoxidation of alkenes using ð-interactions as fundamental factors for the control of the facial selectivity. It was decided to employ cinchona alkaloid derivatives as the basic core of our catalysts. We envisage that the alkene would interact selectively with the aromatic rings of the catalyst to give the corresponding epoxide in good enantiomeric excess. Quinuclidine derived cataysts of simplified structures were synthesised to find the best conditions for the experiments using chiral cinchona derivatives. An important result to be taken into account in the development of the chiral catalysts was the influence of the counterion on the conversion rate. The triflate gave the highest epoxidation rates for trans-â-methylstyrene. The use of a mixture MeOH/ DMM/ H2O led to a two fold increase in reaction rate and is recommended to increase the van der Waals interactions between the aromatic rings of the catalyst and the alkene. New catalyst amd a new epoxidation protocol for the epoxidation of alkenes mediated by dioxiranes have been disscussed .Encouraging results have been obtained from this work.

Thesis (Ph. D.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains ix, 82 p. : ill. Includes abstract. Includes bibliographical references (p. 70-80).

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains ix, 134 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Several novel cascade processes have been designed and developed that involve sequential reactions of imines and iminium ions to form substituted quinolizidine ring systems in a single step from simple and readily available starting materials. The utility and promise of these cascades is evident from their application to extraordinarily concise syntheses of the representative quinolizidine alkaloids (±)-epilupinine, (±)-tashiromine, and (-)-epimyrtine. Within the context of a longstanding interest in aromatic heterocyclic natural product synthesis, a concise synthetic strategy incorporating new tactics for key chemical transformations, as well as novel applications of existing synthetic methods was developed constructing the natural product meloscine. Meloscine was isolated in the 1970's from the New Caledonian plant Melodinus Scandens Forst, which is used in Chinese folk medicine for the treatment of meningitis and rheumatic heart disease. In route to meloscine, a facile synthetic method was developed toward several carboline type indoles. Also, progress has been made toward the total synthesis of the natural product meloscine. / text