ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Synthesis of 2-Substituted Imidazole NucleosidesCondensation of the trimethylsilyl derivatives of 2-substituted diethyl and dimethyl imidazole-4,5-dicarboxylates (3-5 and 7-9) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (2) in the presence of trimethysilyl trifluoromethanesulfonate provided the 2-substituted diethyl and dimethyl 1-(2′,3′, 5′-tri-O-benzoyl-β-D-ribofuranosyl)imidazole-4, 5-dicarboxylates 10-15. These were treated with ammonia to afford the 2-substituted 1-(β-D-ribofuranosyl)imidazole-4,5-dicarboxamides 16-21. Treatment of 2-methyl-(16) and 2-ethyl-1-(β-D-ribofuranosyl)imidazole-4,5-dicarboxamide (17) with fuming nitric acid in oleum at -30° yielded the nitric acid esters 23 and 24. Besides the esterification of the sugar hydroxyl groups one H-atom of the imidazolecarboxamide function at C(5) in these nucleosides was also substituted by the NO2 group.The conformations in solution of 16 and 23 have been determined by 1H- and 13C-NMR. spectroscopy. These studies indicate that the nucleosides exist in dimethyl-sulfoxide solution preferentially in the S-gg-syn-conformation (16) and N-gt-conformation (23). In the crystal structure of nucleoside 23, the ribose was found to be in the O(1′)endo, C(1′)exo twist conformation. The conformation about C(4′), C(5′) is gauche-trans and the molecule exists in the syn form.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19800630602
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