A mixture of 0.145 g (0.24 mmol) of 2-[5-[(3,4-dihydro-4-oxo-8-propyl-2H-1-benzopyran-7-yl)oxy]pentyloxy]-5-(1-oxo-1H-2-benzopyran-3-yl)benzenepropanoic acid ethyl ester in 5 mL of THF and 5 mL of water was treated with 29.8 mg (0.71 mmol) of lithium hydroxide monohydrate and the mixture was stirred for 47 hrs. After being acidified with 16 mL of 3N aqueous sulfuric acid, the resulting mixture was worked up in the usual manner. The crude product was crystallized from hexane-ethyl acetate to give 0.114 g (79.6%) of the title compound as a white solid, mp 178°-182° C.
