Improved solid phase synthesis of luteinizing hormone releasing hormone analogues using 9-fluorenylmethyloxycarbonyl amino acid active esters and catalytic transfer hydrogenation with minimal sidechain protection and their biological activities.

Using mainly 9-fluorenylmethyloxycarbonyl amino acid 2, 4, 5-trichlorophenyl esters in the presence of 1-hydroxybenzotriazole and the solid support p-alkoxybenzyl alcohol resin, synthesis of luteinizing hormone releasing hormone analogues was carried out with minimal side-chain protection. Catalytic transfer hydrogenation was employed for removal of NO2 and Z-groups from Arg and < Glu respectively avoiding the use of HF and this led to good yields. An aromatic, hydrophilic amino acid, D-(p-hydroxyphenyl) glycine was incorporated into luteinizing hormone releasing hormone molecule along with other modifications. The agonistic as well as antagonistic activities of all the peptides have been studied.