Novel Enantiopure ß-Amino Alcohols and ß-Amino Thiols in Asymmetric Catalysis

As the enantioselective synthesis of various compounds is of paramount interest in organic chemistry, this work concentrated on asymmetric catalysis. Moreover, a major focus was on asymmetric organocatalysis as there have been tremendous successes in this field during the last years. This is in accordance with the current trends in the modern chemical research, which is nowadays aiming towards the development of ´greener´ methodologies. In the first part of this work a methodology starting from opening of cyclohexene oxide and based on a simple resolution of a racemic mixture was shown in its utility to synthesize various enantiopure amino alcohols having a cyclohexyl core and bearing either a cis- or a trans-configuration at the stereogenic centres. The amino alcohols were tested for their efficacy in the catalytic asymmetric desymmetrization of meso anhydrides. The dicarboxylic acid hemiesters were afforded in 0-95% yield and 0-83% ee, depending on the catalyst used. In the second part of this work, the application of new technologies for asymmetric transformations was studied. A custom-built simultaneous cooling-microwave irradiation device was applied in the desymmetrization of meso anhydrides in order to accelerate the reaction, but no such effect was observed. Also the possibility of conducting the latter reaction in the solid state was studied. Towards this end, the technology of ball milling was chosen as a method for efficient mixing of the solid reactants and during the time of this work no asymmetric reactions had been conducted in a ball mill. In this work, it was shown that asymmetric reactions can be conducted in solid-state in a ball mill. The scope of the reaction was studied and this methodology was shown to be applicable for a wide variety of anhydrides and alcohols, solid as well as liquid ones. In the third part of this work, a synthetic route towards cis-ß-amino thiols was developed. Starting from the enantiopure trans-2-aminocyclohexanol, via relatively simple reactions it was possible to synthesize various thiols and sulfides. These compounds were then applied as ligands in the ruthenium- and iridium-catalyzed transfer hydrogenation of prochiral ketones. They were shown to be active catalysts, affording in some cases >90% conversion already after 15 minutes, and in all cases ees higher than 80%.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2007

Author dc:creator

• Rantanen, Toni

Contributors dc:contributor

• Bolm, Carsten

• info:eu-repo/classification/ddc/540
• Organische Chemie
• Katalyse
• Chemie
• Organic Chemistry
• Asymmetric Catalysis

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123838%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:62260