The kinetics and mechanism of the acid-catalysed detritylation of nucleotides in non-aqueous solution

Mark A. Russell, Andrew P. Laws, John H. Atherton, Michael I. Page

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The kinetics and mechanism of the deprotection (detritylation) of 5′-O-(4,4′-dimethoxytrityl)-2′-deoxythymidine nucleoside catalysed by dichloroacetic acid to give a 4,4′-dimethoxytrityl carbocation have been studied in toluene, dichloromethane and acetonitrile. There is little or no effect of solvent polarity on the equilibrium and rate constants. Entropies of activation are highly negative ∼-105 J K -1 mol-1 and similarly show little variation with solvent. Addition of small amounts of water to the reaction medium reduces the detritylation rate, presumably through its effect on the solution acidity. All observations are compatible with detritylation occurring through a concerted general acid-catalysed mechanism rather than a stepwise A1 process.

Original languageEnglish
Pages (from-to)52-57
Number of pages6
JournalOrganic and Biomolecular Chemistry
Volume7
Issue number1
DOIs
Publication statusPublished - 2009

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nucleotides
Dichloroacetic Acid
Nucleotides
acids
nucleosides
Kinetics
Acids
Methylene Chloride
Equilibrium constants
kinetics
Toluene
Entropy
Nucleosides
Acidity
acidity
Thymidine
acetonitrile
toluene
Rate constants
polarity

Cite this

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The kinetics and mechanism of the acid-catalysed detritylation of nucleotides in non-aqueous solution. / Russell, Mark A.; Laws, Andrew P.; Atherton, John H.; Page, Michael I.

In: Organic and Biomolecular Chemistry, Vol. 7, No. 1, 2009, p. 52-57.

Research output: Contribution to journalArticle

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T1 - The kinetics and mechanism of the acid-catalysed detritylation of nucleotides in non-aqueous solution

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AU - Page, Michael I.

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AB - The kinetics and mechanism of the deprotection (detritylation) of 5′-O-(4,4′-dimethoxytrityl)-2′-deoxythymidine nucleoside catalysed by dichloroacetic acid to give a 4,4′-dimethoxytrityl carbocation have been studied in toluene, dichloromethane and acetonitrile. There is little or no effect of solvent polarity on the equilibrium and rate constants. Entropies of activation are highly negative ∼-105 J K -1 mol-1 and similarly show little variation with solvent. Addition of small amounts of water to the reaction medium reduces the detritylation rate, presumably through its effect on the solution acidity. All observations are compatible with detritylation occurring through a concerted general acid-catalysed mechanism rather than a stepwise A1 process.

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