Bromine → Acetic acid 2-cyclopentyl-4-(9-bromo-2,3-dimethyl-naphtho[2,3-b]thiophen-4-yl)-phenyl ester

Participants

Reaction Conditions

Reaction Steps

To acetic acid 2-cyclopentyl-4-(2,3-dimethyl-naphtho[2,3-b]thiophen-4-yl)-phenyl ester (2.9 g, 7.7 mmol) in anhydrous methylene chloride (68 mL) was added ferric chloride (66 mg, 0.41 mmol). The reaction mixture was placed under nitrogen and cooled to −78° C. The reaction mixture was protected from light and a solution of bromine (0.44 mL, 8.5 mmol) in anhydrous methylene chloride (11 mL) was added dropwise over a period of 15 min. After stirring at −78° C. for 45 min the reaction was quenched with dilute sodium bisulfite, and then poured into water (200 mL). The resulting mixture was extracted with diethyl ether (300 mL), and the diethyl ether layer was washed with water and then brine. Concentration under reduced pressure and chromatography with petroleum ether:ethyl acetate (95:5) gave the title compound as a white solid (2.7 g, 79%): (CDCl3): δ8.28 (d, 1H), 7.58-7.52 (m, 2H), 7.39-7.34 (m, 1H), 7.29 (d, 1H), 7.18 (dd, 1H), 7.14 and 7.13 (d, 1H), 3.18 (quintet, 1H), 2.44 (s, 3H), 2.40 (s, 3H), 2.06-2.02 (m, 2H), 1.75-1.45 (m containing a singlet at δ1.60, 9H); MS(EI): [M+], 1 bromine isotope pattern, 492/494; Anal. Calc. for C27H25BrO2S: C, 65.72; H, 5.11; N, 0.00. Found: C, 63.18; H, 4.96; N, 0.00.

Provenance & Evidence