Synthesis and characterization of amino protected peptides derived from amino-α- hydroxyiminophosphonates

Diisopropyl 2-amino-1-hydroxyiminoethylphosphonate (2a), derived from glycine, and diisopropyl 4-am1no-1-hydroxyiminobutylphosphonate (2c), derived from GABA, were reacted with Boc-L-Phe-OH by the mixed anhydride method to yield novel peptide analogs diisopropyl 2-(t-Boc-L-Phe)amino-1-hydroxyiminoethylphosphonate (3a) and diisopropyl 4-(t-Boc-L-Phe)amino-1-hydroxyiminobutylphosphonate (3c). Diisopropyl 3-amino-1-hydroxyiminopropylphosphonate (2b), derived from β-Ala, and diisopropyl 2-amino-1-hydroxyiminopropylphosphonate (2d), derived from DL-Ala, were reacted with Boc-DL-Ala-OH by the mixed anhydride method to give peptide analogs diisopropyl 3-(t-Boc-L-Ala)amino-1-hydroxyiminopropylphosphonate (4b) and diisopropyl 2-(t-Boc-L-Ala)amino-1-hydroxyiminopropylphosphonate (4d) respectively. ¹H, ³¹P NMR and FAB Mass spectra of the peptide analogs are reported.