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http://hdl.handle.net/11375/8781
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DC Field | Value | Language |
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dc.contributor.advisor | Harrison, Paul | en_US |
dc.contributor.author | Sun, Sengen | en_US |
dc.date.accessioned | 2014-06-18T16:43:58Z | - |
dc.date.available | 2014-06-18T16:43:58Z | - |
dc.date.created | 2011-03-09 | en_US |
dc.date.issued | 1994-06 | en_US |
dc.identifier.other | opendissertations/3957 | en_US |
dc.identifier.other | 4974 | en_US |
dc.identifier.other | 1862744 | en_US |
dc.identifier.uri | http://hdl.handle.net/11375/8781 | - |
dc.description.abstract | <p>Glycoluril 1 acts as a bifunctional template, allowing efficient and repetitive<br />Claisen-type condensations between attached acyl units. Thus acetoacetyl<br />derivative 3 was prepared from 1 via 2. After conversion to the crotonate<br />derivative 4 (2 steps, β-carbonyl reduction and dehydration), a second cycle of<br />acylation and condensation gave crotonyl-transferred product 5. Repetition ofthe<br />sequence gave the 8-carbon derivative 6. Reduction of 4 with L-Selectride<br />afforded the butyryl derivative 7. allowing further acetylation and condensation<br />reactions leading towards long fatty acid chains. The product ratio from<br />condensation of the acetyl butyryl derivative of 1 is 4:1 in favour of deprotonation<br />of the acetyl group and transfer of the butyryl group. Reaction of 7 with lithium<br />benzyloxide gave recovered 1 and benzyl butyrate. Treatment of crotonyl acetyl</p> <p>[diagram removed]</p> <p>derivative 8 with L-Selectride produced only the acetyl transferred condensation<br />product 9. A similar regioselectivity was observed with L-Selectride reduction of<br />other α,β-unsaturated compounds (e.g., the acetyl acryloyl derivative). Results<br />of isotopic-labelling experiments support an intramolecular acyl transfer<br />mechanism for these condensations. This system mimics some of the features of polyketide and fatty acid synthases, allowing intramolecular acyl transfer and<br />repetitive additions of acetate units to make linear carbon chains while the<br />growing chain remains attached to the template. This is a potentially useful<br />method for the synthesis of some natural products and some useful organic<br />intermediates, such as putative oligoketide biosynthetic precursors.</p> | en_US |
dc.subject | Chemistry | en_US |
dc.subject | Chemistry | en_US |
dc.title | Template-Directed Condensations between Acyl Units | en_US |
dc.type | thesis | en_US |
dc.contributor.department | Chemistry | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
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fulltext.pdf | 11.4 MB | Adobe PDF | View/Open |
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