Palladium-catalyzed coupling between 2-bromo-5-nitropyridine (I) and N-Boc-(S)-2-aminopent-4-ynoic acid methyl ester (II) produces the disubstituted acetylene (III). Simultaneous triple bond and nitro group reduction in (III) is then achieved by transfer hydrogenation employing ammonium formate and Pd/C, to furnish amino ester (IV). After saponification of the methyl ester group of (IV), the resultant carboxylic acid (V) is condensed with 4-(difluoromethylene)piperidine (VI), yielding amide (VII). Cleavage of the N-Boc group of (VII) under acidic conditions gives amine (VIII), which is further acylated by the imido sulfonyl chloride (IX) to produce sulfonamide (X). Finally, ammonolysis of the acetimide function of (X) gives rise to the title compound.