Synthesis of phosphonic analogs of enkephalins. Pentapeptides with COOH replaced by PO3H2 group.

Eight analogs of enkephalins containing the phosphonic analogs of Gly, Leu, Met, Phe and Pro have been synthesized by standard procedures in solution. The key intermediates in the synthesis were pure diastereomers of dialkyl N-L-phenylalanyl/aminoalkanephosphonates obtained from racemic dialkyl aminoalkanephosphonates by coupling with phenylalanine and resolution of the resulting mixture of L, D and L, L dipeptides by means of column chromatography.