Ethyl Acetate → D-2-Amino-5-phenyl-pentanoic acid

Participants

Reaction Steps

To a stirred solution of N-[(1,1-dimethylethoxy)carbonyl]amino-(2S,3R)-(+)-6-oxo-2,3-diphenyl-4-morpholinecarboxylate, (1.0 g, 2.8 mmol) and cinnamyl bromide (2.78 g, 14 mmol) in dry THF (70 mL) at -78° C., was added dropwise sodium hexamethyldisilazide (5.6 mL; 1.0M solution in hexane). The reaction mixture was stirred for 30 minutes, then poured into ethyl acetate (150 mL) and washed with brine, dried over anhydrous magnesium sulfate, filtered and evaporated. The crude product was first washed with warm hexane and then with an ether:hexane (1:1) mixture. The solid material was the desired product. A solution of this intermediate (1.0 g, 2.1 mmol) in CH2Cl2 (2 mL) and TFA (2 mL) was stirred at room temperature for 1 h. The solvents were removed under reduced pressure and the residue was dissolved in saturated aqueous sodium bicarbonate solution and extracted with CHCl3. The organic layer was washed with brine, dried over potassium carbonate, filtered and evaporated to give the amine as a foam which was used without purification. Approximately 0.6 g (1.62 mmol) of this material was dissolved in 40 mL of (2:1) EtOH:THF and hydrogenated under 40 psi using PdCl2 /C for 24 h. The catalyst was filtered off through celite pad and the solvent was evaporated to give the title compound as a colorless solid.

Provenance & Evidence