Thesis--University of Florida. / At head of title: Contract no. W-7405-eng-26. Chemistry Division. "ORNL-3057."

No description available.

No description available.

In this thesis the synthesis of vicinal stereocenters is investigated in two distinct contexts, namely the construction of 3,3-disubstituted oxindoles and the synthesis of b-hydroxy-a-amino acids. Both scaffolds are prevalent in a range of natural products and biologically relevant compounds and, therefore, methods for their synthesis are of great import. First, the construction of 3,3-disubstituted oxindoles using palladium-catalyzed domino reactions is described.  This covers two stereospecific methods for the construction of the desired oxindoles based on domino carbopalladation sequences.  The termination events for these domino reactions are carbonylation or cross-coupling.  In the carbopalladation-carbonylation reaction, we studied the possibilty of suppressing b-hydride elimination for substrates possessing pendant b-hydrogens.  In the carbopalladation-cross-coupling sequence, we examined the role of the boron source and substrate scaffold in the outcome of the reaction.  In both of these methods, an intricate balance of rates needs to be attained in order to achieve the desired domino sequences.  Thus, these investigations offer insight into the rates of the competing reactions, and the factors that influence these processes. Secondly, the stereoselective synthesis of b-hydroxy-a-amino acids is explored.  This has lead to two separate methods for the construction of this scaffold.  We first examined a 1,3-dipolar cycloaddition of azomethine ylides to aldehydes for the construction of syn-b-hydroxy-a-amino esters.  It was found that one set of azomethine ylides reacted through a 1,3-dipolar cycloaddition, while the other set reacted via a direct aldol reaction.  Finally, we studied an asymmetric transfer hydrogenation reaction to provide anti-b-hydroxy-a-amido esters from the corresponding a-amido-b-ketoesters.  Two protocols were developed for the reduction of these substrates, one using triethylammonium formate and the other using sodium formate in an emulsion.  The latter method gives high yields, diastereoselectivities and enantioselectivities for a broad range of substrates. / QC 20120605

The major aim of this thesis has been to contribute to the understanding of the CH$ sb2$/OH/NH$ sb2$ group interactions by means of studies of alcohol-amine mixtures in the gas and liquid phases. / To study these interactions in the gas phase a Burnett type equipment was designed, built and operated at low pressure, obtaining experimental pressure-temperature (P-T) data for various systems including alcohol-amylamine mixtures. The P-T data were reduced by a method developed in this work to give values of second virial coefficients. Measurements on known systems were in excellent agreement with values reported in the literature. A group contribution method for predicting pure compounds and interaction second virial coefficients is presented. This method is equal, or superior to methods already available. / To study the CH$ sb2$/OH/NH$ sb2$ group interactions in the liquid phase, vapor-liquid-equilibrium (VLE) experiments with alcohol-amylamine mixtures were carried out in a Van Ness type apparatus. The raw data were reduced by a novel model free method using the second virial coefficients obtained previously for these mixtures. A group contribution method for predicting vapor-liquid-equilibria of multicomponent multigroup mixtures is proposed. Excellent predictions are obtained with this method. / Finally, computer experiments of Lennard-Jones fluid mixtures were carried out to help in the understanding of the local composition concept. This concept is of fundamental importance not only in the models used in this work but also in numerous other solution models.

No description available.

Heterocycles that contain nitrogen, such as piperidine, pyrrolidine and tropane, are widespread as natural product alkaloids and serve as templates for many bioactive drugs and drug candidates. The intent of this research is to the develop asymmetric syntheses of piperidine-containing syn and anti 1,3-amino alcohols as well as tropinone and tropane-containing derivatives using sulfinimines (N-sulfinyl imines) as precursors for acid-catalyzed cascade cyclizations. Chiral N-sulfinyl b-amino ketones derived from N-sulfinyl b-amino Weinreb amides, serve as novel and direct precursors to syn and anti N-sulfinyl 1,3-amino alcohols through stereoselective reductions. General reduction conditions have been developed for a variety of substrates. This methodology was applied to a concise formal synthesis of the piperidine-containing natural product, (-)-pinidinol, through an intramolecular cascade-cyclization of a masked-oxo N-sulfinyl 1,3-amino alcohol. Special conditions were found for the syn reduction of these substrates. Tropinones and tropanes are structural motifs which encompass many interesting bioactive natural products such as cocaine and scopolamine. The synthesis of these tropinone derivatives, using an asymmetric and intramolecular cascade reaction, allows for facile functionalization of one of the bridgehead carbons. This opens doors to novel derivatives of (-)-cocaine which can be used as potential addiction therapeutics or in new SAR studies of dopamine reuptake transporter blockers. Here a five-membered cyclic imine can be formed through the acid-catalyzed intramolecular cyclization of acyclic ketal-protected N-sulfinyl ketones. After reaction with an acylating agent, the tropinone nucleus can be formed through an intramolecular Mannich reaction of an N-acyl iminium ion. / Chemistry

The development and optimisation of conditions for oxidative Wacker-type cyclisations followed by establishing the reaction scope are reported. Building upon the achievements in the field of oxidative Wacker-type reactions that has recently gathered interest, hydroxylamines and hydrazines were converted to isoxazolidines and pyrazolidines respectively. Secondary hydroxylamines cyclised yielding syn-isoxazolidines with excellent diastereoselectivities, whereas secondary hydrazines cyclised yielding anti-pyrazolidines but still maintained a high level of diastereoselectivity. Additionally, an enantioselective variant was explored. Isoxazolidines were successfully transformed to the corresponding 1,3-amino alcohols, which were further converted to amino sugar derivatives.

The first part of this thesis describes a synthetic strategythat provides all eight possible isomers of a given vic-aminoalcohol starting from vinylepoxides. The value of a generalroute is evident, as several isomers are needed ininvestigations of structure-activity relationships forpharmacologically active derivatives, and for optimizing theperformance of chiral ligands containing the amino alcoholmoiety. Vinylepoxides, obtained in high enantiomeric excess, werering-opened both with inversion and retention ofstereochemistry, delivering two diastereomeric amino alcoholswith high regio- and stereoselectivity. Via ring-closure toaziridines and subsequent regioselective ring-opening withsuitable oxygen nucleophiles, the two remaining amino alcoholswere selectively achieved. Within this study, two efficient protocols for theregioselective and stereospecific aminolysis of vinylepoxideshave been presented. Comparedto previous methods, theseprocedures use milder reaction conditions, shorter reactiontimes, generally give higher yields and are applicable to alarger set of substrates. Furthermore, the ring-closure ofvic-amino alcohols to the corresponding N-H vinylaziridines hasbeen investigated. Three routes have been found useful, whichone is preferred depends on substrate and scale. In the second part of the thesis, the synthetic strategy isapplied on the synthesis of Sphingosine and its regio- andstereoisomers. Moreover, a rapid way of determining relativeconfiguration of vic-amino alcohols is described, which shouldbe of substantial use when amino alcohols are formed bydiastereoselective reactions. amino alcohols, vinylepoxides, vinylaziridines, oxazolines,oxazolidinones, ring-opening, regioselective,diastereoselective, sphingosine, configuration, NMRspectroscopy.

Chiral 1,2-amino alcohols were synthesized via newly developed &ldquo / intramolecular unsaturation transfer&rdquo / using cyclohexanone, propargyl bromide, and various chiral amino alcohols as starting components. These amino alcohols can be potential chiral ligands for many asymmetric transformation reactions. Therefore, their effectiveness as chiral ligands in diethylzinc addition to benzaldehyde and N-diphenylphosphinoyl imines were tested. Various parameters including temperature, solvent, ligand amount etc. were screened for the synthesized chiral ligands. In diethylzinc addition to benzaldehyde high enantioselectivity could not be obtained. When N-diphenylphosphinoyl imines were used as substrate good ee values up to 80% were achieved.