A solution of sodium borohydride (0.035 g., 0.0009 mole) in 0.2N aqueous sodium hydroxide (0.35 ml.) was added dropwise to a solution of 7-[2-oxo-5-(3-oxo-1-octenyl)cyclopentyl]heptanoic acid (0.14 g., 0.0004 mole) in ethanol (3 ml.) and N aqueous sodium hydroxide (0.42 ml., 0.0004 mole). The resulting solution was stirred for 1 day, and then the ethanol was removed in vacuo. A small quantity of water was added, and the solution was extracted twice with diethyl ether (to remove non-acidic material). The aqueous solution was covered with a layer of diethyl ether and acidified to pH 1 by the dropwise addition of concentrated hydrochloric acid, cooling the solution to about 10°C. The ether layer was separated and the aqueous layer extracted twice more with diethyl ether. The combined ether extracts were dried over magnesium sulphate and evaporated to give 7-[2-hydroxy-5-(3-hydroxy-1-octenyl)cyclopentyl]heptanoic acid (0.08 g., 57%), νmax 1700 cm-1 and 980 cm-1 (liquid film), which required no further purification. N.M.R. (approximately 10% solution in deuterochloroform) 0.9 δ (triplet J=5c/s, terminal CH3), 1.1-2.0 δ (broad band, cyclic and chain CH2), 2.3 δ (triplet J=6c/s, CH2C=O) ~ 4.0 δ (broad mutiplet ##EQU5## 5.25 δ (broad singlet, OH), 5.4δ (broad peak ##EQU6##
