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

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Reaction Steps

Trichloromethyl chloroformate (5.40 mL, 44.82 mmol) was added slowly to a solution of 5-chloro-2-(4-methoxy-benzylamino)-nicotinic acid methyl ester (72) (12.5 g, 40.75 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 11.80 g (91%) of 6-chloro-1-(4-methoxy-benzyl)-1H-pyrido[2,3-d][1,3]oxazine-2,4-dione (73) as white solids. MP: 173° C.; 1H-NMR (DMSO-d6): 3.71 (s, 3H), 5.25 (s, 2H), 6.85 (m, 2H), 7.33 (m, 2H), 8.49 (d, J=2.8 Hz, 1H), 8.82 (d, J=2.8 Hz, 1H); EIMS: 319 (M+1).

Provenance & Evidence