Cesium carbonate → 2-(4-{2-[2-(3-Bromophenyl)-5-methyloxazol-4-yl]ethoxy}phenoxy)-2-methylpropionic acid ethyl ester

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Reaction Steps

A mixture of toluene-4-sulfonic acid 2-[2-(3-bromophenyl)-5-methyloxazol-4-yl]ethyl ester, 2-(4-hydroxyphenoxy)-2-methylpropanoic acid ethyl ester (American Home Products U.S. Pat. No. 3,795,691) (7.06 g, 31.5 mmol) and Cs2CO3 (13.3 g, 41.0 mmol) was heated at 55° C. in DMF (45 mL) for 18 h. The reaction was partitioned between ethyl acetate (250 mL) and H2O (250 mL), and the aqueous phase extracted with ethyl acetate (2×100 mL). The combined organic phases were dried (MgSO4) and concentrated under reduced pressure to an oil which was purified by column chromatography (1500 mL SiO2, hexanes to 10% ethyl acetate/hexanes) to provide 2-(4-{2-[2-(3-bromophenyl)-5-methyloxazol-4-yl]ethoxy}phenoxy)-2-methyl propionic acid ethyl ester (6.81 g, 44%) as a off-white solid. Rf=0.39 in 1:4 ethyl acetate:hexanes; 1H NMR (400 MHz, CDCl3) δ8.11 (t, J=1.6 Hz, 1H), 7.89-7.86 (m, 1H), 7.49 (ddd, J=8.0, 2.0, 1.2 Hz, 1H), 7.27 (t, J=8.0 Hz, 1H), 6.80-6.72 (m, 4H), 4.20 (q, J=7.2 Hz, 2H), 4.15 (t, J=6.6 Hz, 2H), 2.92 (t, J=6.6 Hz, 2H), 2.34 (s, 3H), 1.49 (s, 6H), 1.24 (t, J=7.2 Hz, 3H); MS (EI) 510.1 (M+Na)+, 488.1 (M+H)+.

Provenance & Evidence