合成路线1

Nucleophilic displacement of 2-chloro-5-(trifluoromethyl)pyridine (I) with ethanesulfonamide (II) in the presence of K2CO3 in hot DMSO afforded the N-pyridyl sulfonamide (III). Subsequent nitration of (III) with fuming nitric acid in HOAc gave the 3-nitro derivative (IV). Preparation of this intermediate was also reported by displacement of 2-chloro-3-nitro-5-(trifluoromethyl)pyridine (V) with the sodium salt of ethanesulfonamide (II). Subsequent reduction of the nitro group of (IV) to the corresponding 3-aminopyridine (VI) was carried out by means of catalytic hydrogenation, iron in HOAc, or sodium hydrosulfite as the reducing agents. Amine (VI) was coupled either with cyclohexanecarbonyl chloride (VII) or with cyclohexanecarboxylic acid (VIII) in the presence of EDC to produce the cyclohexanecarboxamide (IX). The acidic sulfonamide NH group of (IX) was finally converted to the sodium salt by treatment with NaOH.