A mixture of ethyl 3-(4-((5-bromo-2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)methoxy)phenyl)-2-methylpropanoate (110) (78 mg, 0.17 mmol), diethylamine (0.08 mL, 0.78 mmol), [1,1′-biphenyl]-2-yldi-tert-butylphosphine (16 mg, 0.052 mmol), tris(dibenzylideneacetone) dipalladium (47.6 mg, 0.052 mmol), and sodium t-butoxide (25 mg, 0.26 mmol) in toluene (2 mL) was heated in a pressure tube at 80° C. overnight. Water was added and the reaction was extracted with ethyl acetate and the combined organic layers dried over sodium sulfate, filtered and concentrated in vacuo. The crude compound was purified by flash column chromatography on silica gel with hexanes and EtOAc (50%) to give ethyl 3-(4-((5-(diethylamino)-2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)methoxy)phenyl)-2-methylpropanoate. The ester was dissolved in tetrahydrofuran (1.0 mL), methanol (1.0 mL) and water (3 mL). Lithium hydroxide was added and the reaction was stirred at room temperature for 24 hours. The mixture was acidified with 1M HCl and diluted with EtOAc (3 mL). The organic layer was washed with brine (3 mL), dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo to yield 3-(4-((5-(diethylamino)-2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)methoxy)phenyl)-2-methylpropanoic acid (118). 1H NMR (400 MHz, CDCl3) δ 7.38 (s, 1H), 7.18 (s, 1H), 7.09 (d, J=8.1 Hz, 2H), 6.87 (d, J=8.3 Hz, 2H), 5.04 (s, 2H), 3.84-3.47 (m, 2H), 3.34-3.09 (m, 2H), 3.06 (s, 2H), 3.01-2.89 (m, 1H), 2.78-2.57 (m, 2H), 1.51 (s, 6H), 1.18 (d, J=6.7 Hz, 3H), 1.07 (t, J=6.9 Hz, 6H). LC-MS ESI m/z: found 410.4 [M−H]−.
