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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Chiral additives in the asymmetric Heck reaction

Sellarajah, Shane January 2001 (has links)
No description available.
2

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

Jheengut, Vishal 25 August 2007
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.
3

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

Jheengut, Vishal 25 August 2007 (has links)
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.

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