Methanol → (S)-2-[2,6-Dibromo-4-(6-bromo-benzo[b]naphtho[2,3-d]thiophen-11-yl)-phenoxy]-3-phenyl-propionic acid

Participants

Reaction Steps

Aqueous potassium hydroxide (1 N, 2.40 mL, 2.40 mmol) was added to a stirred solution of (S)-2-[2,6-dibromo-4-(6-bromo-benzo[b]naphtho[2,3-d]thiophen-11 -yl)-phenoxy]-3-phenyl-propionic acid, methyl ester (0.88 g, 1.21 mmol) in THF (12 mL)/methanol (8 mL). After 2 h the solution was concentrated, diluted with water (50 mL) and acidified with 10% aqueous HCl. The reaction mixture was then partitioned between water and ether. The ether phase was concentrated and triturated with ether and pet. ether. It was then recrystalized from methanol to provide the title compound as a white solid (0.54 g, 63%): [a]D25 =-24.81° (10.08 mg/mL CHCl3); NMR (CDCl3); δ8.36 (d, J=8 Hz, 1 H), 7.81 (d, J=8 Hz, 1 H), 7.68 (ddd, J=8, 5, 3 Hz, 1 H), 7.58 (dd, J=10, 2 Hz, 2 H), 7.54-7.48 (m, 2 H), 7.44-7.27 (m, 6 H), 7.16 (ddd, J=8, 7, 1), 6.72 (d, J=8 Hz, 1 H), 5.45 (t, J=7 Hz, 1 H), 3.59 (d, J=7 Hz, 2 H); MS (EI): [M+], 3 bromine isotope pattern, 708 (24%), 710 (80%) 712 (100%) 714 (40%); Anal. Calc. for C31H19Br3O3S: C, 52.35, H, 2.69, N, 0.00. Found: C, 52.05, H, 2.59, N, 0.10. Chiral analytical HPLC determined that this compound had approx. 100% EE [column:Chirobiotic V, 5 micron (4.6 ×250 mm); isocratic, 1:1 ethanol:hexane; flow rate =0.80 mL/min; injection volume =0.3 pL; sample conc. =0.25 mg/mL; retention time, R-enantiomer =21 min; retention time, S-enantiomer =16 min.]

Provenance & Evidence