Lithium Hydroxide → tert-butyl(1S)-5-{[(benzyloxy)carbonyl]amino}-1-(1-hydroxy-2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)pentylcarbamate

Participants

Reaction Steps

28.0 g (45.0 mmol) of (2S)-6-{[(Benzyloxy)carbonyl]amino}-2-[(tert-butoxycarbonyl)amino]-1-({[(1R)-1-phenylethyl]amino}carbonyl)hexyl benzoate was dissolved in 200 mL of dioxane, and a solution of 2.47 g (174 mmol) of lithium hydroxide in 100 mL of water was added. The resulting mixture was stirred for 24 h at room temperature. It was then diluted with 500 mL of ethyl acetate, and washed with 300 mL of 1N hydrochloric acid. The aqeous layer was back-extracted with two 100 mL portions of ethyl acetate. The extracts were then combined with the original ethyl acetate layer, washed with three 200 mL aliquots of saturated aqueous sodium bicarbonate, followed by 100 mL of saturated aqueous sodium chloride, and dried over magnesium sulfate. Volatiles were then removed under vacuum to afford 25.61 g (quantitative crude yield) of tert-butyl (1S)-5-{[(benzyloxy)carbonyl]amino}-1-(1-hydroxy-2-oxo-2-{[(1R)-1-phenylethyl]amino}ethyl)pentylcarbamate as a waxy light yellow solid. 1H NMR (300 MHz, DMSO-d6) δ 7.98-7.88 (m, 1H); 7.68-7.63 (m) and 7.49-7.42 (m) total 1H; 7.35-7.10 (m, 10H); 6.31 (d, J=9 Hz) and 6.02 (d, J=9 Hz) total 1H; 5.62-5.53 (br s) and 5.53-5.42 (br s) total 1H; 4.94 (s, 2H), 4.91-4.83 (m, 1H); 3.87 (br s) and 3.79 (br s) total 1H; 3.72-3.58 (m, 1H); 2.99-2.76 (m, 2H); 1.47-1.10 (m, 18H). ES-LCMS m/z 514 (M+H).

Provenance & Evidence