2' AND 3'-KETONUCLEOSIDES AND THEIR ARABINO AND XYLO REDUCTION PRODUCTS CONVENIENT ACCESS VIA SELECTIVE PROTECTION AND OXIDATION OF RIBONUCLEOSIDES

Article abstract of DOI:10.1016/0040-4020(84)85111-X

A number of 2',5'- or 3',5'-diprotected ribonucleosides and 5'-protected 2'- or 3'-deoxy-β-D-erythro-pentofuranosyl nucleosides have been oxidized to the corresponding 3' or 2'-ketonucleoside derivatives using chromium trioxide/pyridine/acetic anhydride or dimethyl sulfoxide/acetic anhydride.Reduction of the carbonyl functions with sodium borohydride gave the inverted arabino, xylo, or deoxy-threo isomers as predominant products by attack at the less hindered α-face of the sugar ring.Parallel reductions using sodium borodeuteride corroborated the epimeric ratios by demonstrating that complete oxidation of the original hydroxyl groups had occured.The deuterium labeling also aided in making NMR spectral assignments.