N-acetyl 2',3'-dideoxycytidine 5'-acetate → Cytidine, N-acetyl-2',3'-didehydro-2',3'-dideoxy-, 5'-acetate

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To the catholyte reservoir was added 35.0 g (0.081 mol) of 4-(acetylamino)-1-(3'-bromo-2',5'-di-O-acetyl-β-D-xylofuranosyl-2-(1H)-pyrimidinone III(a) ##STR15## R'=CH3, and 1.0 L of 0.25M tetraethylammonium tosylate in acetonitrile. To the anolyte reservoir was added 1.0 L of 0.025M tetraethylammonium tosylate in acetonitrile. Both the catholyte and anolyte were circulated through the electrolytic cell at a flow rate of 200 ml/min/cell. The cell was divided by an anion exchange membrane and the initial current density was 2.4 mA/cm2 at -1.5V. The reaction was followed by TLC and HPLC. During the first 8 hr the desired product N-acetyl 2',3'-dideoxycytidine 5'-acetate started to precipitate from the reaction mixture. The product was removed by filtration and the reaction continued. After 16 hr, this reaction was almost complete. The catholyte mixture was collected and evaporated to dryness at room temperature and 10 mm vacuum. The dried residue was combined with the previously filtered solids. The mixture of product and electrolyte was then dissolved in 200 mL of deionized water. The mixture was extracted with 3×300 ml=900 of methylene chloride. The organic extract was dried over anhydrous sodium sulfate and evaporated to dryness. The residue was triturated with 180 ml of tetrahydrofuran to give 18.12 g (76% yield) of N-acetyl 2',3'-didehydro-2',3'-dideoxycytidine 5'-acetate, IV, ##STR16## R'=CH3, m.p.>300° (dec); [α]D25 +14.7° (c=0.387, DMSO). The product was analyzed by HPLC to give a 99.2% assay.

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