1,2-Dibromo-1,1,2,2-tetrafluoroethane → 8-Bromo-2,3-dihydro[1,4]dioxino[2,3-b]pyridine

A solution of 2,3-dihydro-[1,4]dioxino[2,3-b]pyridine (prepared by the method of H. Neunhoffer et al, Chem., Ber., 1990, 123 (12), 2453) (1.37 g, 10 mmol) in tetrahydrofuran (20 ml) under argon at −78° C. was treated over 15 minutes with a solution of n-butyl lithium (20 mmol) in tetrahydrofuran (8 ml). After 30 minutes a solution of 1,2-dibromo-1,1,2,2-tetrafluoro-ethane (2.6 g, 10 mmol) in tetrahydrofuran (10 ml) was added dropwise over 5 minutes. After a further 30 minutes the cooling bath was removed and saturated aqueous ammonium chloride (20 ml) and ether (20 ml) were added. The mixture was allowed to warm to room temperature then partitioned between ether/water. The organic extract was washed with half-saturated brine, dried and evaporated. The residue was chromatographed on silica eluting with a 0-30% gradient of ethyl acetate in dichloromethane affording a yellow solid (1.1 g, 51%).

1. customAfter a further 30 minutes the cooling bath was removed
2. additionsaturated aqueous ammonium chloride (20 ml) and ether (20 ml) were added
3. customthen partitioned between ether/water
4. extractionThe organic extract
5. washwas washed with half-saturated brine
6. customdried
7. customevaporated
8. customThe residue was chromatographed on silica eluting with a 0-30% gradient of ethyl acetate in dichloromethane affording a yellow solid (1.1 g, 51%)

ORD record

ord-992bb7f1196b40b48075b54466db89d6

Source dataset

uspto-grants-2009_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07622481B2