A mixture of 0.450 mmol of 3-[4-(2-n-butoxy-3,5-di-iso-propylphenyl)-benzo[b]thien-2-yl]-but-2-enoic acid ethyl ester, 3 mL of THF, 3 mL of methanol and 1 mL of LiOH (2N aqueous) was refluxed for 2 hours. After cooling at room temperature, the mixture was acidified to pH=2 and extracted with ethyl acetate. The organic layer was dried over MgSO4 and after evaporation of the solvents, the crude acid was recrystallized from acetonitrile. 3-[4-(2-n-butoxy-3,5-di-iso-propylphenyl)-benzo[b]thien-2-yl]-but-2-enoic acid was isolated as a white solid.
