Tin tetrachloride → {1-Bromo-6-[3-(3,3-dimethyl-butyryl)-benzo[b]thiophen-2-yl]-naphthalen-2-yloxy}-acetic acid ethyl ester

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Reaction Steps

To a 0° C. mixture of (6-benzo[b]thiophen-2-yl-1-bromo-naphthalen-2-yloxy)-acetic acid ethyl ester (5.18 g, 11.7 mmol) in chloroform (270 mL) was added t-butylacetyl chloride (2.0 mL, 14 mmol) and tin (IV) chloride (2.1 mL, 18 mmol). It was refluxed for 23 hours. During reflux, more t-butylacetyl chloride (9.0 mL, 66 mmol) in four portions and tin (IV) chloride (8.4 mL, 71 mmol) in four portions were added. It was then allowed to cool to ambient temperature and poured into ice water. It was diluted with additional chloroform and washed with water and brine. It was then dried with anhydrous magnesium sulfate, filtered and solvent evaporated. The residue was purified by flash chromatography using (1) 100% chloroform, (2) 25–60% methylene chloride in hexane. It was then purified by HPLC using 90% acetonitrile (0.1% trifluoroacetic acid) in water as the mobile phase. Evaporating the solvent and extracting with ethyl acetate, washing with water and brine, drying with anhydrous magnesium sulfate, filtering, concentrating and drying in vacuo at ambient temperature for two hours yielded {1-bromo-6-[3-(3,3-dimethyl-butyryl)-benzo[b]thiophen-2-yl]-naphthalen-2-yloxy}-acetic acid ethyl ester as an amber semi-solid (0.412 g, 6.53%); mass spectrum (+EI, [M+H]+) m/z 539/541. 1H NMR (500 MHz, DMSO-d6): δ8.26 (d, 1H, J=8.81 Hz), 8.07–8.14(m, 3H), 7.91–7.93 (m, 1H), 7.76 (dd, 1H, J=8.81 Hz and 1.97 Hz), 7.45–7.53 (m, 3H), 5.12 (s, 2H), 4.19 (q, 2H, J=7.15 Hz), 2.33 (s, 2H), 1.20–1.25 (m, 3H), 0.76 ppm (s, 9H). Elemental Analysis for C28H27BrNO4S: Calcd: C, 62.34; H, 5.04; N, 0.00; Found: C, 57.16; H, 4.37; N, 0.00.

Provenance & Evidence