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Stereoselective Synthesis of Indazole 2′-Deoxy-β-D-ribonucleosides: Glycosylation of the Nucleobase Anion

✍ Scribed by Frank Seela; Werner Bourgeois

Publisher
John Wiley and Sons
Year
1991
Tongue
German
Weight
529 KB
Volume
74
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

The glycosylation of indazolyl anions derived from 4a, b with 2‐deoxy‐3,5‐bis‐O‐(4‐methylbenzoyl)‐α‐D‐erythro‐pentofuranosyl chloride (5) is described. The reaction was Stereoselective – exclusive β‐D‐anomer formation – but regioisomeric N^1^‐ and N^2^‐(2′‐deoxy‐β‐D‐ribofuranosides) (i.e. 6a and 7a, resp., and 6b and 7b, resp.) were formed in about equal amounts. They were deprotected to yield 8a, b and 9a, b. Compound 1, related to 2′‐deoxyadenosine (3), and its regioisomer 2 were obtained from 8b and 9b, respectively, by catalytic hydrogenation. The anomeric configuration as well as the position of glycosylation were determined by 1D NOE‐difference spectroscopy. The first protonation site of 1 and 2 was found to be the NH~2~ group. The N‐glycosylic bond of 1__H__‐indazole N^1^‐(2′‐deoxyribofuranosides) is more stable than that of the parent purine nucleosides. Compound 1 is no substrate for adenosine deaminase.

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