A solution of (3R)-6-cyclohexyl-3-[3-(ethoxycarbonyl)-1,2,4-oxadiazol-5-yl]hexanoic acid (Preparation 4) (107 mg, 0.31 mmol) in toluene (2 ml) was treated with n-propylamine (250 μl, 3.10 mmol) and the mixture was heated at 125° C. in a sealed vessel for 2 hours. The mixture was cooled to room temperature, diluted with ethyl acetate and washed sequentially with aqueous citric acid solution (5% w/v), water and brine, dried over anhydrous sodium sulphate, filtered and the solvent removed under reduced pressure. The residue was purified by column chromatography on silica gel eluting with a gradient system of dichloromethane:ethyl acetate (80:20) gradually changing to dichloromethane:ethyl acetate (60:40) then to dichloromethane:methanol (90:10) to afford the title compound as an oil (76 mg).
