Sulfuric Acid → 5-Bromo-8-fluoroisoquinoline

Temperature

135 °C

A mixture of 5-bromo-2-fluorobenzaldehyde (15 g, 74 mmol) and 2,2-dimethoxy-ethylamine (7.77 g, 74 mmol) in toluene (142 mL) was heated to reflux for 30 minutes using a Dean-Stark trap to remove water. The solution was then concentrated under vacuum to provide 5-bromo-2-fluorobenzylidene-2,2-dimethoxyethylamine. 5-Bromo-2-fluorobenzylidene-2,2-dimethoxyethylamine and cold concentrated sulfuric acid (28 mL) were added separately, dropwise, over a period of 20 minutes to concentrated sulfuric acid (83 mL) at 140° C. The mixture was stirred at 135° C. for 30 minutes, allowed to cool, and carefully poured onto ice. Filtered to remove solids and the mixture was washed with dichloromethane. The aqueous layer was made basic by cautious addition of 50% sodium hydroxide solution, and extracted with diethyl ether. Combined ether layers were dried (MgSO4), filtered and concentrated under vacuum to provide 310 mg (2%) of the desired product. MS (ESI) m/e 226 (M+H)+.

1. temperatureto cool
2. additioncarefully poured onto ice
3. filtrationFiltered
4. customto remove solids
5. washthe mixture was washed with dichloromethane
6. additionThe aqueous layer was made basic by cautious addition of 50% sodium hydroxide solution
7. extractionextracted with diethyl ether
8. dry with materialCombined ether layers were dried (MgSO4)
9. filtrationfiltered
10. concentrationconcentrated under vacuum

ORD record

ord-4a4735bab34b4fb89d8dfd701f9b5e23

Source dataset

uspto-grants-2008_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07456169B2