Trifluoroacetic acid (5 mL) was added to a solution of tert-butyl 2-((5Z,8Z,11Z,14Z,17Z)-icosa-5,8,11,14,17-pentaenyloxy)-2-methylpropanoate (600 mg, 1.39 mmol) in dichloromethane (20 mL) under nitrogen and the reaction mixture was stirred at room temperature for two hours. Water was added and the aqueous phase was extracted twice with dichloromethane. The combined organic extract was washed with brine, dried (Na2SO4), filtered and concentrated. The residue was purified by flash chromatography on silica gel using a mixture of heptane, ethyl acetate and formic acid (80:20:1) as eluent. The appropriate fractions were concentrated and the residue (135 mg) was purified further by flash chromatography on silica gel using a gradient of 5-10% of a mixture of ethyl acetate and formic acid (95:5) in heptane as eluent. Concentration of the appropriate fractions afforded 80 mg slightly impure product. This material was dissolved in heptane (5 mL), washed twice with water (5 mL), dried (Na2SO4), filtered and concentrated to afford 40 mg (8% yield) of the title compound as an oil. 1H-NMR (300 MHz, CDCl3): δ 0.99 (t, 3H), 1.47 (s, 6H), 1.64 (m, 2H), 2.07 (m, 4H), 2.81-2.88 (m, 8H), 3.46 (t, 2H), 5.29-5.44 (m, 10H); MS (electro spray): 373.3 [M-H]−.
