Water → Nepsilon-tert.butoxycarbonyl-L-lysyl-L-proline isobutylamide

Participants

Reaction Steps

A solution of 6.3 g (0.012 mol) of Nα -benzyloxycarbonyl-Nε -tert.butoxycarbonyl-L-lysyl-L-proline isobutylamide in 100 ml of methanol was hydrogenated for 3 hours in the presence of 0.6 g of 5% palladium/carbon. A solution of 2.2 g (0.012 mol) of adamantane acetaldehyde in 5 ml of methanol was added via a septum cap and the hydrogenation was continued for 16 hours. The catalyst was removed by filtration and the filtrate was evaporated. A solution of the residue in 70 ml of diethyl ether was treated with 60 ml of water containing 2.5 g (0.025 mol) of potassium bicarbonate. 1.85 ml (0.023 mol) of benzyl chloroformate were added and the mixture was stirred vigorously for 1 hour. The organic solution was separated washed with 5% citric acid solution, water, 5% sodium bicarbonate solution and brine, dried over magnesium sulphate and evaporated to give a foam. Chromatography on 150 g of silica gel using n-hexane/ethyl acetate (2:1) yielded 4.4 g (53%) of Nα -(1-adamantylethyl)-Nα -benzyloxycarbonyl)-Nε -tert.butoxycarbonyl-L-lysyl-L-proline isobutylamide as a foam; Rf-value [n-hexane/ethyl acetate (2:1)]: 0.49.

Provenance & Evidence