Isopropylamine → 2-[(3-chlorophenyl)methyl]-9-hydroxy-N-isopropyl-1,8-dioxo-pyrido[1,2-a]pyrazine-7-carboxamide

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Reaction Steps

To a solution of 5-benzyloxy-6-(3-chlorobenzylcarbamoyl)-1-(2,2-dimethoxyethyl)-4-oxo-1,4-dihydropyridine-3-carboxylic acid (25.4 mg) obtained in Example 161, Step 4 in tetrahydrofuran (0.3 ml) were successively added triethylamine (0.021 ml) and thionyl chloride (0.0056 ml) at 0° C. with stirring. After stirring at room temperature for 10 min, the mixture was ice-cooled again and isopropylamine (0.0086 ml) was added. After stirring at room temperature for 30 min, 5% aqueous potassium hydrogen sulfite solution was added, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with brine, dried and concentrated. Trifluoroacetic acid was added to the obtained residue and the mixture was stirred at 70° C. for 5.5, hr. Trifluoroacetic acid was evaporated, toluene was added and the mixture was concentrated, which operations were performed twice. Crystallization from ethyl acetate (2 ml) gave 2-(3-chlorobenzyl)-9-hydroxy-1,8-dioxo-1,8-dihydro-2H-pyrido[1,2-a]pyrazine-7-carboxylic acid isopropylamide (13.6 mg)

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