Synthesis of oxygen‐17 labeled thyrotropin releasing hormone

Abstract

AbstractOxygen‐17 isotope was introduced into the α‐carboxyl group of L‐proline and L‐pyroglutamic acid by acid catalysed exchange of oxygen‐17 from H2 17O or acid hydrolysis of respective amino acid methyl esters in presence of HCl/H2 17O. The α‐amino group of the amino acids were protected by tertbutyloxycarbonylation. Two analogues of thyrotrop in releasing hormone, one enriched with [17O] at the proline carboxamide oxygen (I) and the other at the pyroglutamic acid's amide oxygen (II) were synthesized using Merrifield method of solid phase peptide synthesis.