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Issue 19, 2004
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Halogenated 7-deazapurine nucleosides: stereoselective synthesis and conformation of 2′-deoxy-2′-fluoro-β-d-arabinonucleosides

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Abstract

The stereoselective syntheses of 5-halogenated 7-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine nucleosides 3bd, 4ac as well as 7-deaza-2′-deoxyisoguanosine 2 are described. Nucleobase anion glycosylation of 2-amino-4-chloro-7H-pyrrolo[2,3-d]pyrimidine (5) with 3,5-di-O-benzoyl-2-deoxy-2-fluoro-α-D-arabinofuranosyl bromide (6) exclusively gave the β-D-anomer 7, which was deblocked (→ 8), aminated at C(4) (→ 3a) and selectively deaminated at C(2) to yield 2′-deoxy-2′-fluoro-β-D-arabinofuranosyl 7-deazaisoguanine (2). Condensation of the 5-halogenated 4-chloro-2-pivaloylamino-7H-pyrrolo[2,3-d]pyrimidines 9ac with 6 furnished the N7-nucleosides 10ac together with N2,N7-bisglycosylated compounds 11ac. The former was converted to the corresponding 2,4-diamino-compounds 3bd, and the latter was deblocked by NaOMe/MeOH to yield the 4-methoxy-nucleosides 4ac. Conformational analysis of the sugar moiety of the nucleosides 2 and 3ad was performed on the basis of vicinal [1H,1H] coupling constants. The fluorine atom in the sugar moiety shifts the sugar conformation from S towards N by about 10%, while the halogen substituents in the base moiety increase the hydrophobicity and polarizability of the nucleobases.

Graphical abstract: Halogenated 7-deazapurine nucleosides: stereoselective synthesis and conformation of 2′-deoxy-2′-fluoro-β-d-arabinonucleosides

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Publication details

The article was received on 25 Jun 2004, accepted on 09 Aug 2004 and first published on 09 Sep 2004


Article type: Paper
DOI: 10.1039/B409648G
Org. Biomol. Chem., 2004,2, 2838-2846

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    Halogenated 7-deazapurine nucleosides: stereoselective synthesis and conformation of 2′-deoxy-2′-fluoro-β-D-arabinonucleosides

    X. Peng and F. Seela, Org. Biomol. Chem., 2004, 2, 2838
    DOI: 10.1039/B409648G

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