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Thiopyran route to polypropionates : proline catalyzed aldol reactions of tetrahydro-4H-thiopyran-4-one

The thiopyran route to polypropionates is an attractive strategy that involves a stepwise iterative aldol homologation of tetrahydro-4H-thiopyran-4-one (I) with thiopyran aldehyde (II) followed by desulfurization to rapidly assemble stereochemically complex polypropionate synthons. <p>In chapter 1, the thesis is summarized in the context of relevant background research including; a) the basic principle of the thiopyran route; b) dynamic kinetic resolution of -substituted aldehydes; c) previous syntheses of serricornin; iv) previous syntheses of membrenones.<p>In chapter 2, proline-catalyzed enantioselective direct intermolecular aldol reactions of tetrahydro-4H-thiopyran-4-one with various achiral aldehydes were studied. The results provided insights on the behaviour and stereoselectivity profile of thiopyranone (a crucial starting block in the thiopyran design) in the proline-catalyzed aldol reaction.<p>In chapter 3, inspired by the results of the aldol reaction of ketone (I) with achiral aldehydes, we next investigated the proline-catalyzed asymmetric aldol reactions of (I) with racemic thiopyran aldehyde (II) as a strategy to rapidly prepare enantiomerically pure tetrapropionate synthons without any requirement of enantioenriched aldehyde. The reaction occurred with high enantiotopic group selectivity and dynamic kinetic resolution.<p>In chapter 4, a detailed study to ascertain the scope and limitations of the design strategy described in chapter 3 was extended towards other catalysts, aldehydes and ketones. <p>Finally, applications of the above mentioned strategy towards the synthesis of serricornin and membrenones A and B are elaborated in chapters 5 and 6 respectively.

Identiferoai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-08242007-140053
Date25 August 2007
CreatorsJheengut, Vishal
ContributorsWard, Dale E.
PublisherUniversity of Saskatchewan
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
LanguageEnglish
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://library.usask.ca/theses/available/etd-08242007-140053/
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