To a solution of 2.5 g of the oily product obtained in Example 6 in 30 ml of benzene were added 1.2 g of triethylamine; 0.8 g of benzoyl chloride was then added dropwise with ice-cooling. The mixture was refluxed by heating for 2 hours and, after cooling, an aqueous solution of potassium carbonate was added. The mixture was extracted with benzene. The extract was washed with water, dried over anhydrous sodium sulphate and then concentrated by evaporation under reduced pressure. The resulting oily product was first purified by column chromatography on silica gel (eluent: a 10 : 0.5 by volume mixture of hexane and triethylamine) and then by recrystallization from diethyl ether, giving 1.5 g of Compound 130 as crystals melting at 123° - 124.5° C.
