Cesium carbonate → (S)-2-(4-{2-[5-Methyl-2-(5-methyl-thiophen-2-yl)-oxazol-4-yl]-ethoxy}-benzyl)-2-phenoxy-butyric Acid Ethyl Ester

Participants

Reaction Conditions

Reaction Steps

(S)-3-(4-Hydroxyphenyl)-2-methyl-2-phenoxypropionic acid ethyl ester (255 mg, 0.85 mmol), toluene-4-sulfonic acid 2-[5-methyl-2-(5-methyl-thiophen-2-yl)-oxazol-4-yl]ethyl ester (383 mg, 1.02 mmol) and Cs2CO3 (335 mg, 1.02 mmol) are combined in anhydrous DMF (6 mL) and stirred for 16 h at 55° C. under an atmosphere of nitrogen. The mixture was then cooled and diluted with ethyl acetate (50 mL), and washed with water then brine. The organic layer was dried with MgSO4 and concentrated in vacuo to a viscous tan oil. The residue was purified by flash column chromatography (200 g silica, hexanes to 25% EtOAc/hexanes) to provide the title compound as a colorless oil (201 mg, 47%). 1H NMR (400 MHz, CDCl3) δ 7.39 (d, J=3.4 Hz, 1H), 7.22-7.13 (m, 4H), 6.97 (t, J=7.2 Hz, 1H), 6.85-6.80 (m, 4H), 6.72 (dd, J=3.6, 1.2 Hz, 1H), 4.23-4.17 (m, 4H), 3.26 (A of Abq, J=13.6 Hz, 1H), 3.11 (B of Abq, J=13.6 Hz, 1H), 2.94 (t, J=5.6 Hz, 2H), 2.50 (s, 3H), 2.34 (s, 3H), 1.39 (s, 3H), 1.22 (t, J=7.2 Hz, 3H); MS (EI+) 505.9 (M+H); 637.8 (M+H+Cs).

Provenance & Evidence