N-bromobutanimide → Methyl 2-(bromomethyl)-6-chloro-3-(3-methyl-2,6-dioxo-4-(trifluoromethyl)-2,3-dihydropyrimidin-1(6H)-yl)benzoate

Participants

Reaction Steps

A solution of 11.4 grams (0.030 mole) of methyl 6-chloro-2-methyl-3-[1-methyl-6-trifluoromethyl-2,4(1H,3H)-pyrimidinedion-3-yl]benzoate and 5.4 grams (0.030 mole) of NBS in the presence of 0.03 gram of benzoyl peroxide in 250 mL of carbon tetrachloride was irradiated with a sun lamp as it stirred at reflux for about 18 hours. The reaction mixture was then cooled and washed with water. The organic layer was dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residue. The residue was subjected to NMR analysis, which indicated that the reaction was about 15% complete. The residue was recharged to the reaction vessel and treated with the same amounts of NBS, benzoyl peroxide, and carbon tetrachloride under the same conditions as described above. Upon completion of the second 18 hour reflux period, a small sample was washed with water, dried with magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure to a residue. The residue was subjected to NMR analysis, which indicated that the reaction was about 70% complete. An additional 2.0 grams (0.011 mole) of NBS was added, and the solution was irradiated at reflux for an additional 18 hours. The reaction mixture was then cooled and washed with water. The organic layer was dried with magnesium sulfate, filtered, and concentrated under reduced pressure to a residue. The residue was purified by column chromatography on silica gel, and the fractions containing product were combined and concentrated under reduced pressure, yielding 11.0 grams of subject compound. The NMR spectrum was consistent with the proposed structure.

Provenance & Evidence