Diphosgene → 1-Benzyl-1H-pyrido[2,3-d][1,3]oxazine-2,4-dione

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Reaction Steps

Trichloromethyl chloroformate (2.5 mL, 21 mmol) was added slowly to a suspension of (1) (4 g, 17.5 mmol) in dioxane and refluxed for 8 h under nitrogen atmosphere. The solution was cooled and the solvent was removed under vacuum. The residue was dissolved in dichloromethane and washed by saturated NaHCO3 solution. The organic phase was dried over Na2SO4 and evaporated to yield a residue. The residue was recrystallized by ether to yields 3.02 g (68%) of 1-benzyl-1H-pyrido[2,3-d][1,3]oxazine-2,4-dione (2) as white solids. MP: 168° C.; 1H-NMR (DMSO-d6): δ 5.35 (s, 2H), 7.26 (m, 1H), 7.30 (m, 2H), 7.39 (m, 3H), 8.41 (dd, J=1.5, 7.5 Hz, 1H), 8.72 (dd, J=1.5, 7.5 Hz, 1H); EIMS: 277 (M+23).

Provenance & Evidence