To a solution of the compound obtained in Example 29 (3) (0.0457 g) in N,N-dimethylformamide (1.4 ml), 60% sodium hydride (0.006 g) was added at 0° C. under nitrogen atmosphere and the mixture was stirred for 15 minutes, followed by addition of 4-fluorobenzyl bromide (0.02 ml), and the mixture was stirred for 1 hour. The reaction solution was then poured into water and extracted with ethyl acetate. The organic layer was washed with a saturated aqueous NaCl solution, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The resulting residue was separated using silica gel column chromatography (hexane:ethyl acetate=1:1) to obtain 0.0403 g of the desired product as a white solid.
