Water → (1R,4S)-1-butyrylamino-4-(hydroxymethyl)-2-cyclopentene

Temperature

0 °C

34.7 g of (1R, 4s)-1-amino-4-hydroxymethyl-2-cyclopentene hydrochloride and 2 g of N,N-4-dimethyl-aminopyridine were dissolved in 600 ml of methylene chloride. The solution was cooled to 0° C. 52 g of triethylamine were then added dropwise (5 min). The mixture was stirred for a further 30 min. At 0° C., a solution of 35.2 g of butyryl chloride in 60 ml of methylene chloride was metered into the mixture over the course of 1 h. The mixture was stirred for a further 1.5 h at between 0 and 20° C., and then 600 ml of water were added thereto. Following phase separation, the aqueous phase was extracted with 600 ml of methylene chloride. The combined organic phases were washed 3×500 ml of 10% strength NaOH, then completely evaporated. The dried solid was dissolved in 120 ml of methanol. 5 g of K2CO3 were added to the solution, and the mixture was stirred for a further 2 h at room temperature. The inorganic salts were filtered off and washed with 20 ml of methanol. The filtrate was neutralized with 2N HCl. The suspension was filtered off, and the filter cake was washed with 20 ml of methanol. The filtrate was completely evaporated. The solid residue was dried and crystallized in 150 ml of toluene to give 28.5 g of the title compound. The yield was 67%.

1. customAt 0° C.
2. customwas metered into the mixture over the course of 1 h
3. stirringThe mixture was stirred for a further 1.5 h at between 0 and 20° C.
4. customFollowing phase separation
5. extractionthe aqueous phase was extracted with 600 ml of methylene chloride
6. washThe combined organic phases were washed 3×500 ml of 10% strength NaOH
7. customcompletely evaporated
8. dissolutionThe dried solid was dissolved in 120 ml of methanol
9. addition5 g of K2CO3 were added to the solution
10. stirringthe mixture was stirred for a further 2 h at room temperature
11. filtrationThe inorganic salts were filtered off
12. washwashed with 20 ml of methanol
13. filtrationThe suspension was filtered off
14. washthe filter cake was washed with 20 ml of methanol
15. customThe filtrate was completely evaporated
16. customThe solid residue was dried
17. customcrystallized in 150 ml of toluene

ORD record

ord-b0b7e1d96e71465fb9deb6c19eaae837

Source dataset

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07358073B2