1-Bromo-2-methylpropane → 7-Benzyl-3-(2-methylpropyl)xanthine

Temperature

50 °C

1.5 g (6.2 mmol) of 7-benzylxanthine from stage b) were dissolved in 50 ml of dimethylformamide at 50° C. and treated in portions with 0.149 g (6.2 mmol) of sodium hydride and stirred at 50° C. for one hour. 0.67 ml (6.2 mmol) of isobutyl bromide was added dropwise and the mixture was heated to 80° C. After 5 hours, a further 0.2 ml (1.86 mmol) of isobutyl bromide was added and the mixture was stirred for a further 5 hours. 12 ml of water and 5 ml of methanol were then added, the mixture was stirred at room temperature for 2 hours, a further 60 ml of water were added and the mixture was extracted three times using methyl tert-butyl ether. The organic phases were washed with water, dried using magnesium sulfate and concentrated under reduced pressure and the residue was purified by flash chromatography on a silica gel column, dichloromethane/methanol (99/1).

1. temperaturethe mixture was heated to 80° C
2. waitAfter 5 hours
3. stirringthe mixture was stirred for a further 5 hours
4. stirringthe mixture was stirred at room temperature for 2 hours
5. extractionthe mixture was extracted three times
6. washThe organic phases were washed with water
7. customdried
8. concentrationconcentrated under reduced pressure
9. customthe residue was purified by flash chromatography on a silica gel column, dichloromethane/methanol (99/1)

ORD record

ord-f183b62dcadc441fb61dc8c5b086b4d8

Source dataset

uspto-grants-2001_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06214992B1