Metal based asymmetric catalysis in Baeyer-Villiger oxidations

One of the objectives of the present thesis was to improve the efficiency of an aluminium-catalyzed Baeyer-Villiger oxidation. This system was based on a mediating species formed by enantiopure 2,2'-dihydroxy-1,1'-binaphthyl (BINOL) and Me2AlCl and utilized a hydroperoxide as oxidant. A first attempt towards an optimized version relied upon the modification of the substitution pattern of the binaphthyl ligand. The introduction of electron-withdrawing groups in position 6 and 6' of the binaphthyl scaffold had a positive influence on the enantioselectivity, affording lactones with up to 81% ee at full conversion. A further investigation was undertaken concerning the structure of the oxidant. Modest co-operative effects between the chiral ligand and a chiral hydroperoxide as a result of matched and mismatched combinations were observed. Moreover, a new asymmetric variant of the Baeyer-Villiger rearrangement was devised. The combination of enantiopure BINOL and properly chosen magnesium reagents gave rise to species that were able to mediate the oxidation of prochiral cyclobutanones to the corresponding butyrolactones in high yields and with modest to good enantioselectivity. It was also demonstrated that Baeyer-Villiger reactions can be performed efficiently in compressed CO2 at room temperature using the Mukaiyama system, i.e. oxygen as terminal oxidant and an aldehyde as co-reductant. For instance, cyclohexanone and norbornan-2-one reacted smoothly, yielding the corresponding lactones with 75% and 92% conversion, respectively

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Palazzi, Chiara

Contributors dc:contributor

• Bolm, Carsten

• info:eu-repo/classification/ddc/540
• Bayer-Villiger-Oxidation
• Asymmetrische Reaktion
• Metallkomplexe
• Chirale Verbindungen
• Katalysator
• Kohlendioxid
• Überkitischer Zustand
• Chemie
• Asymmetrische Synthese
• Homogene Katalyse

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-120836%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:59018