To a solution of the compound (28.8 mg) obtained in Example 26 in THF (2.0 ml), Et3N (25.1 μl) was added, methylsulfonyl chloride (9.3 μl) was added at 0° C., and the reaction mixture was reacted at room temperature 24 hours. The reaction mixture was poured into water, and then the product was extracted with ethyl acetate. The organic layer was washed with an aqueous 10% citric acid solution and saturated brine, and dried, and the solvent was evaporated under reduced pressure, and then the residue was purified by preparative HPLC to obtain the title compound.
