Additions stéréosélectives sur des imines : du développement d'un auxiliaire à la catalyse asymétrique

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Additions stéréosélectives sur des imines : du développement d'un auxiliaire à la catalyse asymétrique

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Stereoselections in cyclic β-ketoester alkylations

A hyperconjugative influence may be an additional factor in Z-alkylation being promoted by a syn-axial ester in enolates formed from conformationally immobilised 6-cyclic beta-ketoesters.

Segregation of DNA polynucleotide strands into sister chromatids and the use of endoreduplicated cells to track sister chromatid exchanges induced by crosslinks, alkylations, or x-ray damage.

The method of Matsumoto and Ohta [Matsumoto, K. & Ohta, T. (1992) Chromosoma 102, 60-65; Matsumoto, K. & Ohta, T. (1995) Mutat. Res. 326, 93-98] to induce large numbers of endoreduplicated Chinese hamster ovary cells has now been coupled with the fluorescence-plus-Giemsa method of Perry and Wolff [Perry, P. & Wolff, S. (1974) Nature (London) 251, 156-158] to produce harlequin endoreduplicated chromosomes that after the third round of DNA replication are composed of a chromosome with a light chromatid and a dark chromatid in close apposition to its sister chromosome containing two light chromatids. Unless the pattern is disrupted by sister chromatid exchange (SCE), the dark chromatid is always in the center, so that the order of the chromatids is light-dark light-light. The advent of this method, which permits the observation of SCEs in endoreduplicated cells, makes it possible to determine with great ease in which cell cycle an SCE occurred. This now allows us to approach several vexing questions about the induction of SCEs (genetic damage and its repair) after exposure to various types of mutagenic carcinogens. The present experiments have allowed us to observe how many cell cycles various types of lesions that are induced in DNA by a crosslinking agent, an alkylating agent, or ionizing radiation, and that are responsible for the induction of SCEs, persist before being repaired and thus lose their ability to inflict genetic damage. Other experiments with various types of mutagenic carcinogens and various types of cell lines that have defects in different DNA repair processes, such as mismatch repair, excision repair, crosslink repair, and DNA-strand-break repair, can now be carried out to determine the role of these types of repair in removing specific types of lesions.

Amélioration des propriétés pharmacocinétiques de peptides par différentes alkylations N-terminales

Modélisations moléculaires réalisés avec le logiciel HyperChem 8.

Amélioration des propriétés pharmacocinétiques de peptides par différentes alkylations N-terminales

Modélisations moléculaires réalisés avec le logiciel HyperChem 8.

Asymmetric allylic alkylation by palladium-bisphosphinites

A series of new chiral palladium-bisphosphinite complexes have been prepared from readily available, naturally occurring chiral alcohols. The complexes were used to efficiently carry out catalytic allylic alkylation of 1,3-diphenylpropene-2-yl acetate with dimethyl malonate. The complexes based on derivatives of ascorbic acid carry out enantioselective alkylations, one of which showed an ee as high as 97%. Based on the structural characterization, it can be surmised that strategic placement of phenyl groups is key to higher enantioselectivities.

Synthesis and stereochemical assignments of diastereomeric Ni(II) complexes of glycine Schiff base with (R)-2-(N-{2-[N-alkyl-N-(1-phenylethyl)-amino]acetyl}amino) benzophenone; a case of configurationally stable stereogenic nitrogen

A family of chiral ligands derived from alpha-phenylethylamine and 2-aminobenzophenone were prepared by alkylation of the nitrogen atom. Upon reaction with glycine and a Ni(II) salt, these ligands were transformed into diastereomeric complexes, as a result of the configurational stability of the stereogenic nitrogen atom. Different diastereomeric ratios were observed depending on the substituent R introduced in the starting ligand, and stereochemical assignments were based on X-ray analysis, along with NMR studies and optical rotation measurements.

STUDIES ON ELECTROGENERATION, INSITU ELECTROCHEMISTRY AND SPECTROELECTROCHEMISTRY OF ALKYL COBALT PORPHYRIN

Methyl-, ethyl-, propyl- and n-butyl cobalt porphyrins were electrochemically synthesized and studied byIn-situ cyclic voltammetry and UV-Visible spectro-el ectrochemistry. Rate constants for the alkylations were determined. It was found that the four alkyl saturated tetraphenylchlorin cobalt complexes were formed after electrochemical reduction of the alkyl cobalt porphyrins.

C-H activations via palladacycles

Summary: This chapter contains sections titled: * Introduction: CC Bond Formation via Cyclopalladation Reactions * Stoichiometric CH Activation Chemistry * Catalytic Chemistry * Arylations * Direct CH CH Coupling Reactions * Alkylations * Other Reactions * Conclusion * References

Friedel–Crafts alkylation catalysed by GaCl3-based liquid coordination complexes

Friedel–Crafts alkylation of benzene with 1-decene was catalysed by a new family of liquid Lewis acids: liquid coordination complexes (LCCs). LCCs are prepared by mixing a metal halide (e.g. GaCl3) and a donor molecule (e.g. N,N-dimethylacetamide, urea, or trioctylphosphine oxide), with the metal halide typically used in excess. This leads to the formation of a eutectic mixture comprised of charged and neutral species in a dynamic equilibrium. GaCl3-based LCCs were used in catalytic amounts, giving high reaction rates under ambient conditions, with selectivities to 2-phenyldecane superior to those previously reported in the literature. The influence of reaction conditions and catalyst composition on the reaction rate and selectivity was investigated. Optimised reaction conditions were suggested. This exploratory study offers promise with regard to the development of safer, LCC-based alternatives to HF in industrial alkylations.

Alkylation of Benzene with higher olefins over zeolites: A green route for lab synthesis.

The objective of the present work is to improve the textural and structural properties of zeolite-Y through ion exchange with rare earth metals. We meant to obtain a comparative evaluation of the physicochemical properties and catalytic activity of rare earth modified H-Y, Na-Y, K-Y, and Mg-Y zeolites. Friedel-Crafts alkylations of benzene with higher 1- olefins such as 1-octene, 1-decene, and 1dodecene for the synthesis of linear alkylbenzene (LAB) have been selected for the present study. An attempt has also been directed towards the correlation of the enhancement in 2-phenylalkane formation to the improvement in the textural and structural properties upon rare earth modification for the zeolite-Y. The present method for LAB synthesis stands as an effective Green alternative for the existing hydrofluoric acid technology

"Catalysis by pillared montmorillonites exchanged with transition metals"

The present work is oriented to obtain a comparative evaluation of the physicochemical properties and catalytic activities of iron, aluminium and iron aluminium mixed pillared montmorillonites and their transition metal exchanged analogues. Reactions of industrial importance like Friedel Crafts alkylations, catalytic wet peroxide oxidation of phenol and MTBE synthesis have been selected for the present study. The thesis is structured into seven chapters. First chapter deals with a brief introduction and literature survey on pillared clays. Second chapter explains the materials and methods employed in the work. Results and discussions on the characterisation techniques are described in the third chapter. The subsequent three chapters describe the catalytic activities of pillared clays in the industrially important reactions. Last chapter comprises the summary of the investigations and the conclusions drawn from the earlier chapters