Reaction Steps
2-(4-Benzo[1,2,5]thiadiazol-5-yl-3-chloro-5-cyclopropylmethoxy-phenyl)-4-methyl-pentanoic acid cyclopropylmethyl ester (0.08 g, 0.19 mmol) was dissolved in a mixture of EtOH and H2O (9 mL/1 mL) and KOH (0.1 g, 1.76 mmol) was added. The reaction mixture was refluxed for 2 h and after cooling the solvent was evaporated. Then, 6 N HCl was added to adjust the pH to 5, and the reaction mixture was extracted with EtOAc (3×10 mL). The combined organic phases were dried over MgSO4 and evaporated under reduced pressure to give 2-(4-benzo[1,2,5]thiadiazol-5-yl-3-chloro-5-cyclopropylmethoxy-phenyl)-4-methyl-pentanoic acid as a yellow oil (0.038 g, 55%). 1H NMR (300 MHz, CDCl3/TMS): δ 8.02 (d, J=9.0 Hz, 1H), 7.96 (s, 1H), 7.53 (d, J=9.0 Hz, 1H), 7.13 (s, 1H), 6.89 (s, 1H), 3.81 (d, J=6.4 Hz, 2H), 3.68 (t, J=7.6 Hz, 1H), 2.04-1.96 (m, 1H), 1.78-1.69 (m, 1H), 1.63-1.55 (m, 1H), 1.10-1.00 (m, 1H), 0.97 (d, J=6.4 Hz, 6H), 0.50-0.39 (m, 2H), 0.22-0.12 (m, 2H). 13C NMR (75 MHz, CDCl3/TMS): δ 179.1, 157.2, 154.6, 154.0, 140.5, 136.7, 134.0, 132.9, 127.8, 122.9, 121.6, 120.1, 111.0, 73.4, 49.4, 42.0, 25.9, 22.6, 22.3, 10.0, 3.1.
