L-Isoleucine → tert-Butoxycarbonyl-L-isoleucine

A suspension of 1-tert-butoxycarbonyloxy-6-chloro-1H-benzotriazole (2.7 g.), L-isoleucine (1.3 g) and triethylamine (3.5 ml.) in a mixture of water (8 ml.) and tert-butyl alcohol (12 ml.) was stirred for 2 hours at 60° to 62° C. tert-Butyl alcohol was distilled off from the reaction mixture under reduced pressure and water (15 ml.) was added to the residue. The mixture was adjusted to pH 3 with a citric acid aqueous solution under ice-cooling and extracted with ethyl acetate. The extract was in turn washed with water and a saturated sodium chloride aqueous solution, and then precipitates were filtered off, after which the filtrate was dried over magnesium sulfate. The solution was concentrated and to the residue was added a mixture of ether and petroleum ether (1:1). An insoluble material was filtered off and the filtrate was concentrated under reduced pressure to give N-tert-butoxycarbonyl-L-isoleucine (2.4 g.), oil.

1. distillationwas distilled off from the reaction mixture under reduced pressure and water (15 ml.)
2. additionwas added to the residue
3. temperaturecooling
4. extractionextracted with ethyl acetate
5. washwashed with water
6. customa saturated sodium chloride aqueous solution, and then precipitates
7. filtrationwere filtered off
8. dry with materialafter which the filtrate was dried over magnesium sulfate
9. concentrationThe solution was concentrated and to the residue
10. additionwas added
11. additiona mixture of ether and petroleum ether (1:1)
12. filtrationAn insoluble material was filtered off
13. concentrationthe filtrate was concentrated under reduced pressure

ORD record

ord-099f45caab1a44f58991a64e3c9b41cd

Source dataset

uspto-grants-1977_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04010178