A mixture of (E)-2-(3-hydroxy-4-phenoxybut-1-enyl)bicyclo[3,3,0]octan-6-one (49 mg), the less polar component prepared as described in Reference Example 45 and in the form of (±)-(E)-2β-(3β-hydroxy-4-phenoxybut-1-enyl)bicyclo[3,3,0]octan-6-one, tert-butyldimethylchlorosilane (31 mg), and imidazole (29 mg) in dimethylformamide (0.116 ml) was stirred at the ambient temperature for 2 hours. The mixture was then treated with water (10 ml) and extracted with diethyl ether. The extract was washed with saturated aqueous sodium chloride solution, dried over anhydrous sodium sulphate and concentrated under reduced pressure, to give (E)-2-(3-tert-butyldimethylsilyloxy-4-phenoxybut-1-enyl)bicyclo[3,3,0]octan-6-one (76 mg), in the form of (±)-(E)-2β-(3β-tert-butyldimethylsilyloxy-4-phenoxybut-1-enyl)bicyclo[3,3,0]octan-6-one.
