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 then washed with water and a saturated sodium chloride aqueous solution. The thus formed precipitates were filtered off and then the filtrate was dried over magnesium sulfate. The solution was concentrated and a mixture of ether and petroleum ether (1:1) was added to the residue. 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. washThe extract was then washed with water
6. customThe thus formed
7. customprecipitates
8. filtrationwere filtered off
9. dry with materialthe filtrate was dried over magnesium sulfate
10. concentrationThe solution was concentrated
11. additiona mixture of ether and petroleum ether (1:1)
12. additionwas added to the residue
13. filtrationAn insoluble material was filtered off
14. concentrationthe filtrate was concentrated under reduced pressure

ORD record

ord-deaf4431e51c4220b93d7200c2e73c0d

Source dataset

uspto-grants-1981_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

USRE030752