Site-selective direct arylation of unprotected adenine nucleosides mediated by palladium and copper: insights into the reaction mechanism

Storr, Thomas E., Firth, Andrew G., Wilson, Karen, Darley, Kate, Baumann, Christoph G. and Fairlamb, Ian J.S. (2008) Site-selective direct arylation of unprotected adenine nucleosides mediated by palladium and copper: insights into the reaction mechanism. Tetrahedron, 64 (26). pp. 6125-6137. ISSN 0040-4020

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Abstract

Reaction conditions facilitating the site-selective direct aryl functionalisation at the C-8 position of adenine nucleosides have been identified. Many different aromatic components may be effectively cross-coupled to provide a diverse array of arylated adenine nucleoside products without the need for ribose or adenine protecting groups. The optimal palladium catalyst loading lies between 0.5 and 5 mol %. Addition of excess mercury to the reaction had a negligible affect on catalysis, suggesting the involvement of a homogeneous catalytic species. A study by transmission electron microscopy (TEM) shows that metal containing nanoparticles, ca. 3 nm with good uniformity, are formed during the latter stages of the reaction. Stabilised PVP palladium colloids (PVP=N-polyvinylpyrrolidone) are catalytically active in the direct arylation process, releasing homogenous palladium into solution. The effect of various substituted 2-pyridine ligand additives has been investigated. A mechanism for the site-selective arylation of adenosine is proposed.

Item Type: Article
Uncontrolled Keywords: direct arylation,purines,c–c bond formation,palladium,copper(i) salts
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Pure Connector
Date Deposited: 13 Jan 2017 00:06
Last Modified: 22 Apr 2020 02:26
URI: https://ueaeprints.uea.ac.uk/id/eprint/62040
DOI: 10.1016/j.tet.2008.01.062

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