To a solution of (2Z,4E,6E)-2,6-difluoro-3-methyl-7-(5,5,8,8-tetramethyl-3-propoxy-5,6,7,8-tetrahydro-naphthalen-2-yl)-octa-2,4,6-trienoic acid ethyl ester (Compound 10, 82 mg, 0.18 mmol) in EtOH (2 mL) was added 1M NaOH (1.0 mL). The mixture was heated to 60° C. for 2 h and was cooled to ambient temperature, acidified with 1M HCl, and extracted with EtOAc (×3). The combined organic layer was washed with brine, dried over Na2SO4, and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel (50% EtOAc-hexane) to give the title compound as a pale yellow solid (56 mg, 73%).
