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Studies on the synthesis of dicaffeoylquinic acid conjugates
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dc.contributor.advisor | Botting, Nigel P. | |
dc.contributor.author | Raheem, Kolawole Saki | |
dc.date.accessioned | 2011-10-03T15:01:36Z | |
dc.date.available | 2011-10-03T15:01:36Z | |
dc.date.issued | 2011-11 | |
dc.identifier | uk.bl.ethos.552610 | |
dc.identifier.uri | https://hdl.handle.net/10023/2009 | |
dc.description.abstract | Dicaffeoylquinic acid (DCQA) is a natural polyphenolic compound widely distributed in plants such as coffee beans, which possesses a range of pharmacological activities. Herein, is reported studies undertaken towards the first total synthesis of 3,5-DCQA conjugates. Two synthetic routes were investigated. The first route involves a seven step sequence beginning from quinic acid. The overall yield via this synthetic approach was 30%. The key steps involved in the sequence were a regioselective benzylation of the C-3-hydroxyl group followed by silyl protection of the C-1 and C-4 hydroxyl groups. Deprotection of the benzyl group by hydrogenolysis and opening of the lactone afforded the 3,5-diol. Esterification of the 3,5-diol with 3,4-tert-butyldimethylsilyl caffeoyl chloride afforded the di-ester. Removal of the protecting groups afforded 3,5-DCQA. The second route involved selective protection of the C-3-hydroxyl group with silyl followed by benzylation of the C-1 and C-3 hydroxyl groups. Saponification of the lactone ring followed by benzylation of the carboxylic acid gave the benzyl ester. Silyl deprotection afforded the 3,5-diol. The 3,5-diol was subsequently esterified by refluxing in toluene with commercially available Meldrum’s acid. In the final step, the synthesis of 3,5-DCQA was achieved by a Knoevenagel condensation of 3,4-dihydroxybenzaldehyde and a malonate ester of quinic acid. An efficient method for the synthesis of possible metabolites of quinic acid conjugates was also described. This protocol employs N-(4-methoxyphenyl)-trifluoroacetimidate glucuronyl as the donor. The key reaction in this sequence was the coupling of N-(4-methoxyphenyl)-trifluoroacetimidate glucuronyl with 4-hydroxy-3-methoxy-benzaldehyde. | en_US |
dc.language.iso | en | en_US |
dc.publisher | University of St Andrews | |
dc.rights | Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported | |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/3.0/ | |
dc.subject | Dicaffeoylquinic acids | en_US |
dc.subject | Natural products | en_US |
dc.subject | Plant natural products | en_US |
dc.subject.lcc | QK898.P764R2 | |
dc.subject.lcsh | Plant products--Synthesis | en_US |
dc.subject.lcsh | Plant polyphenols | en_US |
dc.subject.lcsh | Chlorogenic acid | en_US |
dc.title | Studies on the synthesis of dicaffeoylquinic acid conjugates | en_US |
dc.type | Thesis | en_US |
dc.type.qualificationlevel | Doctoral | en_US |
dc.type.qualificationname | PhD Doctor of Philosophy | en_US |
dc.publisher.institution | The University of St Andrews | en_US |
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