USE OF HOEC ACTIVE ESTERS IN SOLIDPHASE PEPTIDE SYNTHESIS——THE SYNTHESIS OF GROWTH HORMONE RELEASING PEPTIDE

N-hydroxysuccinimide (HOSU) active esters have gained wide application in peptide synthesis, especially in the synthesis of longer peptides by segment conden sation, for they can avoid racemization during coupling processes. However, the HOSU active ester method is prone to side reactions, forming undesirable by-products such as succinimide-oxycarbonyl-alanine N-hydroxysuccinimide ester (Ⅰ) in activating steps and compound (Ⅱ) in the coupling steps sterically hindered by amino acids (proline, valine, isoleucine, etc.).