The two naturally occurring cyclopropene fatty acids, sterculic and malvalic, have been synthesized. The cyclopropene ring was made by inserting a methylene unit into an acetylenic linkage. The synthesis of methyl sterculate was repeated using diethyl aluminum chloride, diazomethane, and methyl stearolate. Methyl malvalate was totally synthesized. Diethyl malonate was condensed with 1, 5-dibromopentane to give 7-bromoheptanoic acid. 1-Decyne was reacted with 7-bromoheptanoic acid to give 7-heptadecynoic acid. 7-Heptadecynoic acid was esterified with diazomethane. The cyclopropene ring was generated using diethyl aluminum chloride and diazomethane. The reaction worked very well and in most cases the yields exceeded 50 percent. / Graduation date: 1966

The relationship between aqueous activity coefficients (log γ(w)) and different physico-chemical properties has been studied for a number of solutes by both empirical correlations as well as by applying existing theoretical models. The solute properties selected have been classified into three categories: geometrical, polar, and electrostatic. The solutes chosen were divided into two major groups: (a) Training Set. Structurally simple compounds, i.e., each containing only one functional group, and (b) Test Set. A series of drugs and pollutants covering a wide variety of functional groups. The Training Set is in turn formed by four sub-sets of structurally related solutes, each representative of typical data sets used in the literature for solubility studies. Linear relationships were found for polar and geometric parameters in agreement with those reported in the literature. However, although the overall correlations are good, the quality of the regressions among the sub-sets is not uniform. The generality of the relationships obtained with the Training Set was tested by applying the obtained expressions to estimate log γ(w) of the solutes of the Test Set. It was found that the parameters of the theoretical models are the only ones whose relationship with log γ(w) is maintained for both the Training and the Test sets. The theoretical models used are: octanol-water partition coefficient estimated by both Rekker's (parameter LOGP) and by Leo's (parameter PCLOGP) methods; the solubility group contributions method of Wakita et al. (1986) (parameter WAKITA); the Linear Solvation Energy Relationships model (parameter KAMLET), and the UNIFAC model. The theoretical approaches were evaluated based on two criteria: accuracy of predictions and range of applicability. The accuracy of predictions was quantitated by a prediction coefficient, P², which although analogous to regression coefficient (R²) is far less flexible. Prediction coefficient is sensitive not only to scatter of the predictions but also to the systematic errors of the model being tested. The range of applicability was quantitated by the fraction (f) of solutes within the data set for which estimates by the given methodology are possible. The Accuracy-Generality Product (AGP) defined as the product of P² and f was used as the overall criterion for evaluation. The results indicated that the quality of predictions of the theoretical models as determined by the AGP is PCLOGP > LOGP > WAKITA > UNIFAC > KAMLET, for both the Training and Test sets.

No description available.

The syntheses of many cycloalkene and cycloalkeneone annelated DHPs have been achieved. A late ring formation approach was used to synthesize the dicycloalkeneone annelated DHP 63 (Scheme 4) and the unsymmetrical dicycloalkeneone annelated DHPs 70a and 70b (Scheme 5). To synthesize the other ring annelated DHPs, a more versatile early ring approach was employed. Through an asymmetrical coupling followed by a series of standard transformations, the cyclopentene-, cyclohexene-, cyclopentenone- and cyclohexenone-annelated DHPs 64 , 118 , 130 , 131 were synthesized (Schemes 13 and 15). Similarily, the dicycloalkene and dicycloalkenone annelated DHPs such as 41 , 42, 123, 124 and 136 were obtained by a symmetrical coupling followed by a series of standard transformations (Schemes 12, 14 and 16). Other than the cycloalkene or cycloalkenone annelated DHPs, the acyclic tetra-substituted DHPs 142 and 143 (Scheme 17) were also synthesized as model compounds. As well, the asymmetrical DHPs 148 and 149 (Scheme 18), having a benzene and a cyclopentenone annelation or with a benzene and a cyclopentenone annelation, were also synthesized to test the annelation effect with a combination of a benzene and a five-membered ring. In the cycloalkene and cycloalkenone annelated DHP series, it was demonstrated that the [pi]-bond fixation effect could be indirectly probed by the internal methyl proton chemical shifts. These are based on the ring current of DHP and the magnitude of bond fixation depends on the annelating ring size, the coplanarity of the carbonyl group with the [pi]-system of DHP (for the cycloalkenone annelated DHPs) and the relative arrangement of the annelated rings (cisoid versus transoid for the diannelated compounds). Thus, when the ring size varied from four to seven in the cycloalkene- and dicycloalkenene annelated DHP series, the cyclohexene ring has the strongest bond fixation effect. When the ring size varied from five to seven in the cycloalkenone- and the dicycloalkenone-annelated DHP series, the cyclopentenone annelated DHPs have the strongest bond fixation effect. In the mono-cycloalkenone annelated DHP series (ring size =5 to 7), the Kekulé structures of the cycloalkenone annelated DHPs were determined by the vicinal coupling constant (3Jhh) to adopt an endocyclic structure (the double bond appears at the ring junction between the DHP and the annelating ring). For the diannelated DHP derivatives, the cisoid arrangement of ring annelation always has a stronger bond fixation effect compared to that of a transoid arrangement in almost all cases. In this thesis work, the use of DHP as a sensitive NMR probe was successfully demonstrated in that its internal methyl proton chemical shift responds to a change of ring current caused by different ring annelations. It is so sensitive, that even the very small perturbation on ring annelation (by cycloalkanes) can be sensed. DHP is a better NMR probe molecule than benzene because the chemical shifts of the internal methyl protons of DHP are less seriously affected by any effects such as geometrical distortion, rehybridization, steric compression, hyperconjugation and through space effects as probed by the ¹H and ¹³C-NMR spectroscopies in benzocycloalkenes. The ring annelation effect probed by DHP is closer to a pure [pi]-effect due to a change in ring current which is different from benzene, which is a mixture of both α- and [pi]-effects... / Graduate

M.Sc. (Chemistry) / Please refer to full text to view abstract

Allylic substitution is an important procedure for carbon-carbon, carbon-nitrogen and carbon-oxygen bond formation, and palladium-mediated allylic substitution reactions have previously been employed in the synthesis of a range a physiologically active and natural products. 2,5-Dicarbon substituted 2,5-dihydrofurans have not to date been synthesised by palladium-mediated allylic substitution reactions. It was found in the first part of the work that allylic substitution reactions of 2,5-diacetoxy-2,5-dihydrofuran with a tertiary carbon nucleophile did not result in the desired mono-substitution product due to the elimination of acetic acid from the product, to form the aromatised furan derivative. In an attempt to differentiate between the two potential leaving groups on the dihydrofuran, one of the acetate groups was displaced in a palladium-mediated allylic substitution reaction. This approach was also intended to inhibit the aromatisation reaction. The desired product 2-acetoxy-5-phenoxy-2,5-dihydofuran was obtained. The palladium-mediated allylic substitution reactions of this product with a range of tertiary carbon nucleophiles provided the desired mono-substituted dihydrofuran products in good yield with minimal by-products being detected. The substitution of the phenoxy-leaving group with a carbon nucleophile, however, was not achieved under a range of reaction conditions. Other more electrondeficient phenol derivatives were used in the initial substitution reactions but due to time constraints the work could not be completed in the current study. This would hopefully have increased the leaving group ability of the phenoxy group and the desired disubstituted dihydrofuran would have been achieved, and this will be the subject of further work in this regard. Milder reaction conditions were applied to 2,5-diacetoxy-2,5-dihydrofuran in its reaction with a tertiary carbon nucleophile. The desired mono-substituted mono acetoxy products were obtained in reasonable yields when column chromatography was performed at –15 °C and the silica was neutralised with Et3N. These mono-acetoxy products were reacted with a range of tertiary carbon nucleophiles and the desired disubstituted dihydrofurans could be prepared in reasonable yields. One-pot reactions were investigated by using three equivalents of nucleophile and in most cases the desired symmetrical dihydrofuran was achieved. This result prompted the investigation into the synthesis of disubstituted dihydrofurans in a one-pot reaction by successive addition of two carbon nucleophiles with 2,5- diacetoxy-2,5-dihydrofuran. The disubstituted dihydrofurans were isolated in higher yields than the two-pot procedure and the complex purification procedure developed was not necessary. This study, therefore, allowed for the synthesis of a range of symmetrical and unsymmetrical dicarbon substituted dihydrofurans. This methodology will later be applied to the synthesis of a range of natural products. / Prof. D.B.G. Williams

Kwok Ka-chu. / Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 53-56.

Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 59-62.

Typescript. / Digitized by Kansas Correctional Industries

Shen, Hao. / "July 2007." / n and 0 in "4fn/d0" in title is superscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 207-220). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.