To the suspension of 1.75 g of 4-(6-carbomethoxyhexyl)-5-(3-hydroxy-1-trans-octenyl)-thiazole (Ic, R1 = H) in 35 ml of a 0.2 M phosphate buffer of pH 7.5, 175 mg of the lipase enzyme specified in Example 5, 17.5 mg of the sodium salt of taurocholic acid and 1.75 ml of a 10 % solution of gum arabic were added. The mixture was then shaken at 25° C in a screening shaker desk at 260 revolutions/minute and an amplitude of 2 cm for 24 hours, whereafter the reaction mixture was diluted with 100 ml of water, acidified with citric acid and extracted with 3 × 70 ml of ethyl acetate. The ethyl acetate extract was dried over sodium sulphate and evaporated in vacuo. The obtained 1.95 g of evaporation residue was purified by chromatography on a column prepared with 50 g of silicic acid, using mixtures of n-heptane and ethyl acetate whose ethyl acetate content was gradually increased, as the eluting solvent. 4-(6-Carboxyhexyl)-5-(3-hydroxy-1-trans-octenyl)-thiazole (ID, R1 = H) was eluted from the column by a mixture consisting of 70 % ethyl acetate and 30 % n-heptane. Thus, 1.25 g of a product of chromatographic purity was obtained which was recrystallized from a mixture of diethyl ether and n-hexane. 30
