Backbone-modified oligopeptidic bioregulators. The synthesis and configuration of thioamide, amidoxime, cyanoamidine, and amidrazone analogs of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe-OR)

Reaction conditions for the synthesis of thioamide, amidoxime, and N-substituted amidine analogs of the peptide bond are described. Several new amidine analogs of the chemotactic peptide f-Met-Leu-Phe-OR were synthesized using the thioamides as precursors. The assignment of the E/Z configuration was accomplished by nuclear magnetic resonance. The biological activity of these analogs is briefly described.