Hydrochloric Acid → HCID 22842819, compound

Participants

Reaction Steps

Benzyl 3-(S)-N,N-dibenzylamino-2-(R)-fluorobutanoate (26.2 g, 66.8 mmol) in 370 mL of methanol containing 5.6 mL of concentrated hydrochloric acid is connected to a Parr hydrogenation apparatus with 2.62 g of palladium hydroxide as catalyst and hydrogenated in two lots at 50 psi. The lots are combined and filtered through a pad of celite. The celite is washed with water and methanol and the combined filtrates are concentrated in vacuo to give a yellow oil. The crude amino acid is taken up in 290 mL of water and treated with sodium carbonate (15.6 g, 140 mmol) and benzyl chloroformate (12.0 g, 70 mmol). After stirring for 4.5 hours, another 7.8 g of sodium carbonate is added and the reaction allowed to stir an additional 18 hours. The basic solution is washed with ether and then acidified with 500 mL of 1 hydrochloric acid. The resulting mixture is extracted with ether. Drying over magnesium sulfate followed by removal of the ether in vacuo affords 12.7 g of the desired N-benzyloxycarbonyl-3-(S)-amino-2-(R)-fluorobutanoic acid.

Provenance & Evidence