Reaction Steps
5-(2-Chlorophenyl)-5-(6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)-2,2-dimethylpentanoic acid ethyl ester (1.0 g, 2.46 mmol) was dissolved in water (5 mL) and ethanol (5 mL) that contained potassium hydroxide (1 g). The mixture was heated to reflux for 6 hours. After cooling to room temperature, the ethanol was removed under reduced pressure. Water (25 mL) was added and the solution was acidified to pH=5 to 6 with concentrated hydrochloric acid. The product was extracted with dichloromethane (2×25 mL). The combined dichloromethane extracts were dried over sodium sulfate, filtered, and concentrated. The crude product (1.06 g) was purified by column chromatography on silica gel (20 g), eluting with heptane/ethyl acetate (1:1). The product containing fractions were combined, concentrated, and dissolved in dichloromethane (25 mL). The dichloromethane solution was acidified with hydrochloric acid (2N) in diethyl ether (6 mL). The solvents were removed under reduced pressure. The remaining solid was dried to a constant weight at room temperature under high vacuum to provide 5-(2-chlorophenyl)-5-(6,7-dihydro-4H-thieno[3,2-c]pyridin-5-yl)-2,2-dimethylpentanoic acid, hydrochloride salt (Compound Ia hydrochloride, 0.71 g, 69.6% yield) as a off-white solid. 1H NMR (300 MHz, DMS-d6/TMS): δ=12.20 (br s, 1H), 11.83 (br s, 0.5H), 11.61 (br s, 0.5H), 8.10 (m, 1H), 7.77-7.41 (m, 4H), 6.97 (d, 1H, J=4.5 Hz), 6.81 (d, 1H, J=4.5 Hz), 4.90-4.70 (m, 1.5H), 4.42-4.37 (m, 0.5H), 4.11-4.01 (m, 1H), 3.90-3.80 (m, 0.5H), 3.51 (m, 0.5H), 3.20-2.84 (m, 2H), 2.37 (m, 1H), 2.14 (m, 1H), 1.28 (m, 1H), 1.04 (s, 3H), 1.02 (s, 3H), 0.90 (m, 1H). (mixture of rotational isomers). 13C NMR (75 MHz, DMS-d6/TMS): δ=177.64, 134.50, 131.23, 130.89, 129.72, 129.38, 128.02, 127.33, 125.06, 124.68, 64.62, 63.52, 54.63, 49.73, 48.54, 47.93, 47.20, 40.72, 35.21, 25.90 (d), 24.78, 24.37, 21.79, 21.31 (d), 14.99. MS (MMI-TOF): Calculated for C20H25NO2Cl2S (MH+): 378.1289, found 378.1271. CHN analysis: Calculated; 57.97 C, 6.08 H, 3.38 N, 17.11 Cl, found; 56.07 C, 6.25 H, 3.12 N, 18.55 Cl, Best Fit for CHN Data: C20H25Cl2NO2S+0.65 H2O+0.05 HCl
