Preparation of the pyridylpiperazine moiety starts by aromatic displacement of chlorine from 2-Chloro-3-nitropyridine by piperazine to give 3. The secondary amine is then protected as its BOC derivative by reaction with Di-tert-butyl dicarbonate (Boc anhydride) to give 4. The nitro group is then reduced by catalytic hydrogenation. Reductive alkylation with acetaldehyde in the presence of lithium cyanoborohydride gives the corresponding N-ethyl derivative. The protecting group is then removed by reaction with TFA. Reaaction of the resulting amine with the imidazolide derivative of 5-Methoxy-3-indoleacetic acid affords the amide reverse transcriptase inhibitor, atevirdine.
^Romero, D. L.; Morge, R. A.; Biles, C.; Berrios-Pena, N.; May, P. D.; Palmer, J. R.; Johnson, P. D.; Smith, H. W.; Busso, M.; Et. Al. (1994). "Discovery, Synthesis, and Bioactivity of Bis(heteroaryl)piperazines. 1. A Novel Class of Non-Nucleoside HIV-1 Reverse Transcriptase Inhibitors". Journal of Medicinal Chemistry37 (7): 999. doi:10.1021/jm00033a018.