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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.

IT : oxidations of alkanes and alkenes by T butyl hydroperoxide or molecular oxygen catalysed by polybenzimidazole supported metal complexes

Ólason, Gunnar B. January 1997 (has links)
No description available.

Environmentally friendly oxidation catalysis using supported reagents

Butterworth, Andrew J. January 1997 (has links)
No description available.

Synthesis of a clickable FDG precursor for PET in vivo imaging

Säberg, Alexander January 2015 (has links)
The thesis of this study describes a synthesis way to produce an alkyne equipped clickable precursor of 2-deoxy-2-fluoro-D-glucose (FDG) with a beta-configuration. This FDG-derivate is produced with a clickable link in purpose to be used in PET in vivo imaging. The product was synthesized by acetylation protection and further epoxidation on the glucose analog D-Glucal. Glycosylation occurred by electrophilic reaction of propargyl alcohol and configuration of the product was ensured during Lattrell-Dax inversion.

New systems for catalytic asymmetric epoxidation

Parkes, Genna Alexandria January 2007 (has links)
No description available.

Applications of new methods for the synthesis of #beta#-hydroxy-#alpha#-amino acids

Adams, Zoe Michelle January 1999 (has links)
No description available.

Aspects of stereochemical control in organic synthesis

Bish, E. H. January 1985 (has links)
No description available.

Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

Anees, Muhammad, Nayak, Sanjit, Afarinkia, Kamyar, Vinader, Victoria 27 November 2018 (has links)
Yes / The stereochemical outcome of the epoxidation of Δ14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the stereochemical outcome of the epoxidation. / We thank University of Bradford for a bursary (MA).

Epoxidierung von Olefinen mit Wasserstoffperoxid : Neue katalytische Systeme auf der Basis fluorierter Alkohole /

Hüttenhain, Daniel. January 2007 (has links)
Thesis (doctoral)--Universität Köln, 2007.

A study of rhodium catalyzed hydroborations and sulfur ylide epoxidations

Edwards, David Ryan 17 September 2007 (has links)
A rhodium-catalyzed process has been developed in which mixtures of internal and terminal olefins are isomerized and hydroborated in one step yielding the corresponding terminal pinacolboronates. Homologation and subsequent oxidation regiospecifically affords the terminal aldehyde in what amounts to a one-pot CO free hydroformylation. Good overall yields are obtained in all substrates examined. In a related study, mechanistic aspects of the rhodium catalyzed hydroboration of vinyl arenes have been probed. A combination of substituent effects (Hammett study), deuterium labeling studies and heavy atom isotope effects has demonstrated mechanistic differences in the hydroboration of electron rich and electron poor substrates. The results of the study further demonstrate the differences in reaction mechansim for hydroborations mediated with catecholborane versus pinacolborane. The Corey-Chaykovsky reaction, in which an aldehyde and a sulfur ylide are coupled to yield an epoxide has proven to be a versatile and valuable method for the production of epoxides. The reaction between benzaldehyde and benzyldimethylsulfonium tetrafluoroborate has been subjected to a kinetic analysis. Activation parameters were determined for the reaction and a large negative ΔS‡ of -35 cal/mol/K was calculated for the epoxidation of benzaldehyde. A large carbon kinetic isotope effect of 1.026 and an inverse deuterium isotope effect of 0.93 were determined for the reaction. A large positive Hammett ρ of +2.50 was found for the epoxidation of various substituted benzaldehydes by competition experiments. These results aided in the identification of the rate limiting step as addition of the ylide species to benzaldehyde. In a separate, although related study, the mechanism of the collapse of hydroxysulfonium salts has been examined with regard for implications in the epoxidation of aldehydes. The anti-diastereomer reacted with complete retention of stereochemistry and no crossover, while the syn-diastereomer gave crossover products along with cis and trans epoxides. Deprotonation and re-protonation on the carbon of the alpha-hydroxy sulfonium ylide was responsible for production of the trans epoxide as demonstrated by deuterium labeling. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-08-29 17:56:36.642

The development of a general method for the asymmetric epoxidation of electron deficient alkenes

Elston, Catherine L. January 1996 (has links)
No description available.

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