Diphosgene → 6-fluoro-1-(4-methoxy-benzyl)-1H-pyrido[2,3-d][1,3]oxazine-2,4-dione

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Reaction Steps

Trichloromethyl chloroformate (11.41 mL, 94.63 mmol) was added slowly to a solution of 5-fluoro-2-(4-methoxy-benzylamino)-nicotinic acid ethyl ester (68) (24 g, 78.86 mmol) in dioxane and refluxed for 4 h under nitrogen atmosphere. The solution was cooled and the solvent was removed under vacuum. The residue was recrystallized by ether to yield 21.5 g (90%) of 6-fluoro-1-(4-methoxy-benzyl)-1H-pyrido[2,3-d][1,3]oxazine-2,4-dione (69) as white solids. MP: 143° C.; 1H-NMR (DMSO-d6): δ 3.71 (s, 3H), 5.27 (s, 2H), 6.85 (m, 2H), 7.35 (m, 2H), 8.40 (dd, J=2.8, 6.8 Hz, 1H), 8.82 (d, J=2.8 Hz, 1H); EIMS: 303 (M+1).

Provenance & Evidence