反应详情

To a solution of 6-propionyl-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine (3.4 g) and 30% hydrogen bromide-acetic acid (10 ml) in acetic acid (50 ml) was added pyridinium hydrobromide perbromide (5.12 g) at ambient temperature and the mixture was stirred for 2 hours at the same temperature. The reaction mixture was poured into water. The resultant precipitate was collected by filtration and dissolved in a mixture of ethyl acetate and tetrahydrofuran. The organic solution was washed with a saturated aqueous solution of sodium bicarbonate and brine. The solvent was dried over magnesium sulfate and removed in vacuo to afford a crystalline residue, which was washed with diisopropyl ether to give 6-(2-bromopropionyl)-2-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazine (3.8 g).

1. filtrationThe resultant precipitate was collected by filtration
2. dissolutiondissolved in a mixture of ethyl acetate and tetrahydrofuran
3. washThe organic solution was washed with a saturated aqueous solution of sodium bicarbonate and brine
4. dry with materialThe solvent was dried over magnesium sulfate
5. customremoved in vacuo
6. customto afford a crystalline residue, which
7. washwas washed with diisopropyl ether