Heck and Sonogashira couplings in aqueous media – application to unprotected nucleosides and nucleotides
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///////Heck, Sonogashira, Green chemistry, Water
Amongst
all synthetic nucleosides having high potential biological activities,
C5-modified pyrimidines and C7-deaza or C8-modified purines have been
particularly studied. These main chemical modifications have been
developed using palladium cross-coupling reactions. This review focus on
both Heck and Sonogashira cross-coupling of nucleosides using different
aspects of the twelve principles of green chemistry: use of aqueous
medium and no protection/deprotection steps.
Heck cross-coupling reaction in aqueous solution was developed using only Pd(II) as a pre-catalyst in water and in CH3CN/H2O.
The first Heck cross-coupling reaction starting from deprotected nucleoside was reported in 1998 by Barbas et al. [16]. Starting from 5-iodo-2’-deoxyuridine (1) and allyl amide 2 in presence of Na2PdCl4 (80 mol%) as palladium source in sodium acetate buffer (0.1 M, pH = 5.2) as solvent at room temperature for 18 hours, (E)-[3-(trifluoroacetamido)propenyl]-2’-deoxyuridine (3) was isolated in 44% yield (Scheme 1). Compound 3 is a precursor of functionalized dUTP derivatives that are substrates for thermostable DNA polymerases. Nucleoside analogue 3 was obtained a few years later in the same range of yields by Williams et al. using the same experimental conditions[17].
Scheme 2
Synthesis of ferrocene analogue 65 and 66.
Scheme 3
Synthesis of phenylalanine analogues 67 and 68.
The first Heck cross-coupling reaction starting from deprotected nucleoside was reported in 1998 by Barbas et al. [16]. Starting from 5-iodo-2’-deoxyuridine (1) and allyl amide 2 in presence of Na2PdCl4 (80 mol%) as palladium source in sodium acetate buffer (0.1 M, pH = 5.2) as solvent at room temperature for 18 hours, (E)-[3-(trifluoroacetamido)propenyl]-2’-deoxyuridine (3) was isolated in 44% yield (Scheme 1). Compound 3 is a precursor of functionalized dUTP derivatives that are substrates for thermostable DNA polymerases. Nucleoside analogue 3 was obtained a few years later in the same range of yields by Williams et al. using the same experimental conditions[17].
Scheme 2
Synthesis of ferrocene analogue 65 and 66.
Scheme 3
Synthesis of phenylalanine analogues 67 and 68.
Heck and Sonogashira couplings in aqueous media – application to unprotected nucleosides and nucleotides
2Department of Chemistry, University of Hull, England HU6 7RX, UK
The electronic version of this article is the complete one and can be found online at:http://www.sustainablechemicalprocesses.com/content/3/1/3
http://www.sustainablechemicalprocesses.com/content/3/1/3
http://www.sustainablechemicalprocesses.com/content/3/1/3
- Transformations Intégrées de la Matière Renouvelable (TIMR) - EA 4297Compiègne, France
LEN Christophe
Head of Research, Scientific Council
Head of Research, Scientific Council
Centre de recherche de Royallieu, Compiègne Cedex
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