To a stirring solution of 695 mg (6.04 mmol) of thiotetronic acid in 10 mL of dimethylformamide is added 902 μL (6.47 mmol) of triethylamine and 240 mg (1.97 mmol) of 4-dimethylaminopyridine at 0° C. Next, 1.37 g (7.13 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 2.0 g (7.19 mmol) of γ-linolenic acid are added and the reaction mixture is stirred overnight at room temperature. The reaction is acidified with 1.0N HCl and extracted three times with diethyl ether. The combined organic layers are washed with brine, dried over Na2SO4, filtered, and concentrated in vacuo. The residue was subjected to HPLC chromatography (2 inch Dynamax silica gel column, 25 mL/min) eluting with 100% ethyl acetate to give 1.8 g (79%) of 4-hydroxy-3-[(Z,Z,Z)-1-oxo-6,9,12-octadecatrienyl]-2(5H)-thiophenone as an oil.
