Cyanogen Bromide → N2-(tert-butoxycarbonyl)-N5-cyano-L-ornithine tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 6.1 g (14.44 mmol) N5-((Benzyloxy)carbonyl-N2-(tert-butoxycarbonyl-L-ornithine tert-butyl ester in 100 mL ethyl acetate was added 1.0 g 10% palladium on carbon. The suspension was shaken at 22° C. under 50 psi H2 for 45 minutes in a 500 mL Parr bottle. The catalyst was removed by filtration through celite. The resulting solution was concentrated to yield a crude oil. The oil was disolved into 50 mL of diethyl ether and added dropwise to a 0° C. stirred solution of 1.52 g (14.3 mmol) of cyanogen bromide in 30 mL ether. The solution was stirred for 2 h, poured into aqueous sodium bicarbonate, and extraced with ether. The ether solution was dried (magnesium sulfate), concentrated, and purified by silica gel chromatography (100 g, 230-400 mesh silica gel). Elution with a gradient of ethyl acetate in hexanes (30%-60%) gave 3.0 g (67% yield) N2-(tert-butoxycarbonyl)-N5-cyano-L-ornithine tert-butyl ester as an oil.

Provenance & Evidence