40 ml of dichloromethane was added to a mixture of 2.0 g (5.94 mM) of 2-decyl-5-(3-fluoro-4-hydroxyphenyl)-1,3,4-thiadiazole and 0.61 g (5.97 mM) of pentanoic acid. Under stirring at room temperature, 1.21 g (5.86 mM) of N,N'-dicyclohexylcarbodiimide (DCC) and 0.05 g of 4-pyrrolidinopyridine were successively added to the above mixture, followed by stirring for 19 hours at room temperature. After the reaction, precipitated N,N'-dicyclohexylurea was recovered by filtration, washed with dichloromethane and added to the filtrate. The resultant dichloromethane solution was subjected to distillation under reduced pressure to obtain a residue. The residue was purified by silica gel column chromatography (eluent: benzene) and recrystallized from ethanol to obtain 1.40 g of 2-decyl-5-(3-fluoro-4-pentanoyloxyphenyl)-1,3,4-thiadiazole (Yield: 56.9%). ##STR132##
