Photosubstitution of cymantrenylalanine as a tool in peptide chemistry. Synthesis and biological activity of new GnRH analogs.

Beyond its aromatic character and important hydrophobicity, cymantrenylalanine, a metallocenic amino-acid, can be easily photosubstituted with phosphine and phosphite ligands to readily yield new analogs with different hydrophobicity and steric hindrance. The incorporation of phosphine and phosphite ligands is described. As an illustration of the offered possibilities, the synthesis and the biological activity of two new GnRH analogs modified in position 6 are reported.