Claisen condensation of acetophenone (I) with diethyl oxalate affords the dioxo ester (II). This is condensed with 4-(methylsulfonyl)phenylhydrazine (III) to form the diaryl pyrazole (IV). Ester group reduction in (IV) by means of LiAlH4 provides alcohol (V), which is converted to the corresponding mesylate (VI) upon treatment with methanesulfonyl chloride and Et3N

Displacement of 3,5-difluorobromobenzene (VII) with the sodium alkoxide of benzyl alcohol yields the benzyl ether (VIII). Metalation of (VIII) with butyllithium, followed by addition to tetrahydropyran-4-one (IX) furnishes the carbinol adduct (X). This is converted to the methyl ether (XI) by alkylation with iodomethane in the presence of NaH. Then, hydrogenolysis of the O-benzyl group of (XI) over Pd(OH)2 provides phenol (XII). Finally, condensation between phenol (XII) and mesylate (VI) gives rise to the title compound