Horner-Emmons condensation of 1,4-dibenzyl-2-piperazinecarboxaldehyde (I) with phosphonate (II) gave piperazineacrylate (III). Subsequent double bond hydrogenation and hydrogenolysis of the benzyl groups of (III) produced the spontaneous cyclization of the resulting amino ester to furnish the diazabicyclononanone (IV). Finally, condensation of amine (IV) with p-fluorobenzenesulfonyl chloride (V) yielded the title sulfonamide.