3,5-Dibromosalicylaldehyde → 6,8-dibromo-2H-chromen-2-one

To a suspension of 3,5-dibromosalicylaldehyde (100 g, 357 mmol) in acetic anhydride (164.8 mL, 1.8 mol) was added triethylamine (45 mL, 375 mmol). The reaction solution was heated overnight at reflux under argon. The solution was cooled to room temperature and a solid mass formed. The dark brown reaction mixture was washed with hot hexanes (3×300 mL) and aqueous saturated sodium bicarbonate. The resulting solid was dissolved in EtOAc (2L) and washed with water. The organic layer was dried (sodium sulfate) and concentrated to give a brown solid that was collected by filtration. The solid was dried in vacuo to give substantially pure 6,8-dibromocoumarin (94.2 g, 87% yield).

1. temperatureThe reaction solution was heated overnight
2. temperatureat reflux under argon
3. customa solid mass formed
4. washThe dark brown reaction mixture was washed with hot hexanes (3×300 mL) and aqueous saturated sodium bicarbonate
5. dissolutionThe resulting solid was dissolved in EtOAc (2L)
6. washwashed with water
7. dry with materialThe organic layer was dried (sodium sulfate)
8. concentrationconcentrated
9. customto give a brown solid
10. filtrationthat was collected by filtration
11. customThe solid was dried in vacuo

ORD record

ord-21f855ff417749658818bf8c06f9c96a

Source dataset

uspto-grants-2001_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06172256B2