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.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-08242007-140053 |
| Date | 25 August 2007 |
| Creators | Jheengut, Vishal |
| Contributors | Ward, Dale E. |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-08242007-140053/ |
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