合成路线1

Friedel-Crafts acylation of methyl 4-phenylbutyrate (I) with 5,5,6,6,6-pentafluorohexanoyl chloride (II) in the presence of AlCl3 produced ketone (III). This was converted to oxime (IV) upon treatment with hydroxylamine hydrochloride and pyridine, and subsequently reduced to amine (V) by catalytic hydrogenation over Raney nickel. Alternatively, ketone (III) was reduced to alcohol (VI) employing NaBH4. Chlorination of (VI) with SOCl2, followed by displacement with NaN3 furnished azide (VII). Then, reduction of the azido group of (VII) by means of PPh3 provided an alternative route to amine (V). Acylation of amine (V) with 4-fluorobenzenesulfonyl chloride (VIII) gave rise to sulfonamide (IX). The methyl ester group of (IX) was finally hydrolyzed with NaOH yielding the title carboxylic acid.