Diisopropylamine → Tert-Butyl 1-(4-bromobutyl)cyclopropanecarboxylate

21.2 ml (52.7 mmol) of a 2.5 M solution of n-butyllithium in n-hexane were added dropwise to a solution, cooled to −78° C., of 7.4 ml (52.7 mmol) of diisopropylamine in 20 ml of abs. THF. During the addition, the reaction temperature was kept below −60° C. After 30 min of stirring at −60° C. to −70° C., this solution was added dropwise to a solution, cooled to −78° C., of 5.0 g (35.2 mmol) of tert-butyl cyclopropanecarboxylate and 15.2 g (70.3 mmol) of 1,4-dibromobutane in 20 ml of abs. THF. After the end of the addition, cooling was removed and the mixture was slowly warmed to RT with stirring. After a further 5 h of stirring at RT, the reaction mixture was added to saturated aqueous ammonium chloride solution. The mixture was extracted three times with dichloromethane. The combined organic phases were dried over magnesium sulfate and concentrated under reduced pressure. The product was purified by chromatography on silica gel (mobile phase cyclohexane/dichloromethane 50:1). This gave 4.62 g (44.6% of theory) of the target compound.

1. additionDuring the addition
2. customwas kept below −60° C
3. additionthis solution was added dropwise to a solution
4. additionAfter the end of the addition
5. temperaturecooling
6. customwas removed
7. stirringwith stirring
8. stirringAfter a further 5 h of stirring at RT
9. additionthe reaction mixture was added to saturated aqueous ammonium chloride solution
10. extractionThe mixture was extracted three times with dichloromethane
11. dry with materialThe combined organic phases were dried over magnesium sulfate
12. concentrationconcentrated under reduced pressure
13. customThe product was purified by chromatography on silica gel (mobile phase cyclohexane/dichloromethane 50:1)

ORD record

ord-98bf01fada40465aa71b9c9a59653943

Source dataset

uspto-grants-2014_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08642592B2