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New Methods for the...
New Methods for the Synthesis of Vicinal Stereocenters : Palladium-Catalyzed Domino Reactions and Asymmetric Transfer Hydrogenation
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- Seashore-Ludlow, Brinton, 1982- (författare)
- KTH,Organisk kemi,Peter Somfai
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- Peter, Somfai, Professor (preses)
- KTH,Skolan för kemivetenskap (CHE)
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- Booker-Milburn, Kevin, Professor (opponent)
- University of Bristol, School of Chemistry
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(creator_code:org_t)
- ISBN 9789175013749
- Stockholm : KTH Royal Institute of Technology, 2012
- Engelska 75 s.
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Serie: Trita-CHE-Report, 1654-1081 ; 2012:27
- Relaterad länk:
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- NATURVETENSKAP -- Kemi -- Organisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Organic Chemistry (hsv//eng)
Nyckelord
- asymmetric synthesis
- domino reactions
- palladium-catalyzed reactions
- oxindoles
- amino alcohols
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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