Acetic Acid → Tert-butyl 1-{2-[4-(methoxycarbonyl)phenyl]ethyl}-5-oxo-d-prolinate

Participants

Reaction Steps

To a solution of H-D-Glu(OtBu)-OtBu, commercially available from Bache (0.5 g, 2.23 mmol) in MeOH (15 mL) were added 4-carbomethoxyphenylacetaldehyde (obtained from methyl 4-formyl benzoate as described in Nair et al., 1989) (0.4 g, 2.23 mmol), acetic acid (0.15 mL, 2.67 mmol), and NaCNBH3 (3.3 mL, 1.0 M THF solution, 3.3 mmol). The resulting solution was stirred at RT for 3 h then was diluted with EtOAc (100 mL) and washed with water (50 mL), and brine (50 mL). The organic solution was dried over sodium sulfate and concentrated in vacuo. The crude oil was diluted with xylene and the solution refluxed for 5 h. This solution was concentrated under reduced pressure and purified by silica gel column chromatography using EtOAc/hexane as eluent to afford the title compound (0.75 g, 75%) as a white solid. Rj 0.45 (EtOAc/hexane 1/1); 1H NMR (CDCl3) δ 1.47 (s, 9H), 1.95-2.05 (m, 1H), 2.10-2.20 (m, 1H), 2.25-2.35 (m, 1H), 2.40-2.50 (m, 1H), 2.80-3.00 (m, 2H), 3.10-3.20 (m, 1H), 3.82 (dd, 1H), 3.91 (s, 3H), 3.90-4.01 (m, 1H), 7.25 (d, 2H), 7.96 (d, 2H).

Provenance & Evidence