Phenylalanine, 1,1-dimethylethyl ester → 2-[(3-Bromo-thiophen-2-ylmethyl)-amino]-3-phenyl-propionic acid tert-butyl ester

Participants

Reaction Steps

To a stirred solution of 2-Amino-3-phenyl-propionic acid tert-butyl ester (50.6 mg, 0.229 mmol) in ethanol (1 mL), were added 3-Bromo-thiophene-2-carbaldehyde (50 mg, 0.208 mmol.) and acetic acid (21 μL). The reaction mixture was stirred at room temperature under nitrogen for 2 hrs as the progress of imine formation was monitored by TLC. Then, sodium cyanoborohydride (20 mg, 0.312 mmol) was added. The mixture was acidified with sodium bicarbonate and then extracted with dichloromethane. After removal of the solvent, the crude product was purified by silica plate (hexane/ethylacetate 90%:10%) to give 2-[(3-Bromo-thiophen-2-ylmethyl)-amino]-3-phenyl-propionic acid tert-butyl ester in 80% yield: 1H NMR (Varian 400 MHz, CDCl3) δ7.23 (m, 6H, ArH), 6.90 (d, 1H, J=5.3 Hz, thiophenH), 4.00 (d, 1H, J=14.6 Hz, NCH2), 3.85 (d, 1H, J=14.6 Hz, NCH2), 3.48 (m, 1H, CHCH2), 3.00 (m, 2H, CHCH2), 1.37 (s, 9H, tBu).

Provenance & Evidence