To a solution of 4-(9-bromo-2,3-dimethyl-naphtho[2,3-b]thiophen-4-yl)-2,6-dimethyl-phenol (5.0 g, 12.1 mmol), (S)-2-hydroxy-3-phenylpropionic acid, methyl ester (3.3 g, 18.3 mmol), and triphenylphosphine (4.8 g, 18.3 mmol) in anhydrous benzene (50 mL) at room temperature under nitrogen was added dropwise diethyl azodicarboxylate (2.6 mL, 18.3 mmol) over a period of 25 min. The reaction mixture was heated for 2 h, then stirred at room temperature for 3 days. The crude reaction mixture was adsorbed onto silica gel and chromatographed twice with petroleum ether:ethyl acetate (95:5) to yield the title compound as a white foamy solid (4.5 g, 65%): NMR (DMSO-d6): δ8.18 (d, 1H), 7.64 (ddd, 1H), 7.53-7.43 (m, 2H), 7.38-7.24 (m, 5H), 7.00 (s, 2H), 4.80 (t, 1H), 3.58 (s, 3H), 3.31 (m, 2H), 2.42 (s, 3H), 2.24 (s, 3H), 2.19 (s, 3H), 1.55 (s, 3H); MS(EI): [M+], 1 bromine isotope pattern, 572/574; Anal. Calc. for C32H29BrO3S: C, 67.01; H, 5.10; N, 0.00. Found: C, 66.33; H, 5.09; N, 0.09; Analytical HPLC indicates a major component (94.39%).
