| Abstract
| - The diastereospecific chemical syntheses of uridine-2‘,3‘,4‘,5‘,5‘ ‘-2H5 (21a), adenosine-2‘,3‘,4‘,5‘,5‘ ‘-2H5 (21b), cytidine-2‘,3‘,4‘,5‘,5‘ ‘-2H52H5 (21c), and guanosine-2‘,3‘,4‘,5‘,5‘ ‘-2H5 (21d) (>97 atom %2H at C2‘, C3‘, C4‘, and C5‘/C5‘ ‘) have been achieved for their use in the solution NMR structuredetermination of oligo-RNA by the Uppsala “NMR-window” concept (refs a−c, 5a, 6), in which asmall 1H segment is NMR-visible, while the rest is made NMR-invisible by incorporation of thedeuterated blocks 21a−d. The deuterated ribonucleosides 21a−d have been prepared by thecondensation of appropriately protected aglycone with 1-O-acetyl-2,3,5-tri-O-(4-toluoyl)-α/β-d-ribofuranose-2,3,4,5,5‘-2H5 (19), which has been obtained via diastereospecific deuterium incorporation at the C2 center of appropriate d-ribose-2H4 derivatives either through an oxidation−reduction−inversion sequence or a one-step deuterium−proton exchange in high overall yield (44% and 24%,respectively).
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