Cesium carbonate → 3-{2-(2-tert-Butoxycarbonylamino-ethyl)-4-[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethoxy]-phenyl}-propionic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 3-[2-(2-tert-butoxycarbonylamino-ethyl)-4-hydroxy-phenyl]-propionic acid methyl ester (0.807 g, 2.50 mmol) and toluene-4-sulfonic acid 2-(5-methyl-2-phenyl-oxazol-4-yl)-ethyl ester (1.34 g, 3.74 mmol) in DMF (5 mL) was added Cs2CO3 (1.22 g, 3.74 mmol). The suspension was stirred at 65° C. for 48 h, quenched with H2O (200 mL), and extracted with EtOAc (3×100 mL). The combined organics were dried (Na2SO4) and concentrated to a residue, which was purified on silica gel chromatography (hexanes/EtOAc 9/1 to 8/2 to 6/4) to afford the title compound as a colorless oil (0.90 g, 71%). 1H NMR (400 MHz, CDCl3): δ 1.42 (s, 9H), 2.37 (s, 3H), 2.54 (t, 2H, J=7.8 Hz), 2.77 (t, 2H, J=7.8 Hz), 2.88 (t, 2H, J=6.8 Hz), 2.96 (t, 2H, J=6.8 Hz), 3.33 (˜dt, 2H, J=6.8 Hz), 3.65 (s, 3H), 4.20 (t, 2H, J=6.8 Hz), 6.70 (br s, 1H), 6.72 (d, 1H, J=8.3 Hz), 7.05 (d, 1H, J=8.3 Hz), 7.39-7.44 (m, 3H), 7.95-7.98 (m, 2H). MS (ES+) m/z [M+H]+.

Provenance & Evidence