Peracetic Acid → Ethyl 6-(3-chloro-4-fluorobenzyl)-3,4-dihydroxy-5-oxo-5,6,7,8-tetrahydro-2,6-naphthyridine-1-carboxylate

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Reaction Conditions

Reaction Steps

To a stirred solution of ethyl 6-(3-chloro-4-fluorobenzyl)-4-hydroxy-5-oxo-5,6,7,8-tetrahydro-2,6-naphthyridine-1-carboxylate (5.0 g; see Example 12, Step 6) and sodium acetate (0.89 g) in acetic acid (90 mL) was added peracetic acid (28 mL). The mixture was then heated at 50° C. overnight. The mixture was cooled to 5° C. and saturated NaHSO4 (17 mL) added, keeping the temperature at less than 25° C. The mixture was concentrated to 50% original volume and partitioned between tert-butyl methyl ether (100 mL) and water (50 mL). The organic phase collected and the volatiles evaporated. The residue was dissolved in toluene (50 mL) and volatiles evaporated, the residue dissolved in toluene (50 mL) and evaporation repeated. Finally the residue was dissolved in toluene (20 mL). Acetic anhydride (3.9 mL) was added and the mixture heated at reflux until complete by HPLC analysis. The mixture cooled to ambient temperature and sodium ethoxide in ethanol (20 mL) was added. The reaction mixture stirred overnight. 2N HCl (31 mL) was added and the title product isolated by filtration.

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