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Direct Amino Acid-Catalyzed Asymmetric Synthesis of Polyketide Sugars
Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
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2005 Ingår i: Angewandte Chemie International ed., ISSN 1433-7851, Vol. 44, nr 9, s. 1343-1345Artikel i tidskrift (Refereegranskat) Published
Ort, förlag, år, upplaga, sidor
2005. Vol. 44, nr 9, s. 1343-1345
Identifikatorer
URN: urn:nbn:se:su:diva-23701OAI: oai:DiVA.org:su-23701DiVA, id: diva2:194028
Anmärkning
Part of urn:nbn:se:su:diva-449Tillgänglig från: 2005-04-07 Skapad: 2005-04-07Bibliografiskt granskad
Ingår i avhandling
1. Direct Amino Acid-Catalyzed Enantioselective α-Oxidation Reactions and Asymmetric de novo Synthesis of Carbohydrates
Öppna denna publikation i ny flik eller fönster >>Direct Amino Acid-Catalyzed Enantioselective α-Oxidation Reactions and Asymmetric de novo Synthesis of Carbohydrates
2005 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The ability of amino acids to form nucleophilic enamines with aldehydes and ketones has been used in the development of asymmetric α-oxidation reactions with electrophilic oxidizing agents. Singlet molecular oxygen has for the first time been asymmetrically incorporated into aldehydes and ketones, and the products were isolated as their corresponding diols in good yields and ee’s. Organocatalytic α-oxidations of cyclic ketones with iodosobenzene and N-sulfonyloxaziridine were also possible and furnished after reduction the product diols in generally low yields and in low to good ee’s. Amino acids have also been shown to catalyze the formation of carbohydrates by sequential aldol reactions. For example, proline and hydroxy proline mediate a highly selective trimerisation of α-benzyloxyacetaldehyde into allose, which was obtained in >99 % ee. Non linear effect studies of this reaction revealed the largest permanent nonlinear effect observed in a proline-catalyzed reaction to date. Moreover, polyketides were also assembled in a similar fashion by an amino acid-catalyzed one-pot reaction, and was successful for the trimerisation of propionaldehyde, however the sequential cross aldol reactions suffered from lower selectivities. This problem was overcome by the development of a two-step synthesis that enabled the formation of a range of polyketides with excellent selectivities from a variety of aldehydes. The method furnishes the polyketides via the shortest route reported and in comparable product yields to most multi-step synthesis. All polyketides were isolated as single diastereomers with >99 % ee. Based on the observed amino acid-catalysis, amino acids are thought to have taken part in the prebiotic formation of tetroses and hexoses.

Ort, förlag, år, upplaga, sidor
Stockholm: Institutionen för organisk kemi, 2005
Nyckelord
Organo catalysis
Nationell ämneskategori
Organisk kemi
Identifikatorer
urn:nbn:se:su:diva-449 (URN)91-7155-035-6 (ISBN)
Disputation
2005-04-28, sal G, Arrheniuslaboratorierna, Svante Arrhenius väg 14-18, Stockholm, 10:00
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Handledare
Tillgänglig från: 2005-04-07 Skapad: 2005-04-07Bibliografiskt granskad

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