L-Isoleucine → tert-Butoxycarbonyl-L-isoleucine

Participants

Reaction Steps

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.

Provenance & Evidence