Methanol → 2-[2-(5-Bromo-2-methoxy-phenyl)-ethyl]-thiophene-3-carboxylic acid

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To a solution of 2-methyl-thiophene-3-carboxylic acid (8.01 g, 56.0 mmol, 1.0 equiv) in THF (56 mL) at −78° C. was added a solution of lithium diisopropylamide (LDA; 2M, 56 mL, 112.0 mmol, 2 equiv). The orange solution was allowed to stir for 1 hr and then a solution of 4-bromo-2-bromomethyl-1-methoxybenzene (17 g, 73 mmol, 1.3 equiv) in THF (50 mL) was added dropwise via cannula. The solution was allowed to stir at −78° C. for one hour and then warmed to room temperature. The reaction was quenched by the addition of water and ethyl acetate. The phases were separated and the organic phase was washed with brine, dried over Na2SO4, filtered, and concentrated to give a yellow oil. Addition of methanol caused precipitation of a white solid, which was filtered and dried to give 2-[2-(5-bromo-2-methoxy-phenyl)-ethyl]-thiophene-3-carboxylic acid (5.3 g, 15.5 mmol, 27%). 1H NMR (300 MHz, d6-DMSO) δ 12.59 (s, 1H), 7.31 (dd, J=8.7, 5.7 Hz, 1H), 7.26 (dd, J=6.6, 5.4 Hz, 2H), 7.21 (d, J=2.4 Hz, 1H), 6.88 (d, J=9.0 Hz, 1H), 3.71 (s, 3H), 3.27-3.35 (m, 2H), and 2.79-2.88 (m, 2H). LCMS ES− 339 (M−1), 341 (M+1).

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