Synthesis of 14 C‐ and 14 C 3 ‐labelled Org 37462

Org 37462 (1) is the active ingredient in Orgalutran ® , an innovative product that reduces the time of treatment in in vitro fertilization from four to less than two weeks. Org 37462 is a synthetic decapeptide containing several amino acids that are unnatural in stereochemistry and/or in structure. The synthesis, starting with a ProtectingGroup‐ D ‐Ala‐resin, is a typical solid state synthesis. For the conduction of several metabolism studies, Org 37462 had to be labelled with carbon 14. It was decided to label D ‐3‐(2‐naphthyl)alanine, the last amino acid to be coupled to the resin. We report the synthesis of [ 14 C]‐ and [ 14 C 3 ]‐Org 37462, starting from 2‐bromo‐[ 14 C‐methyl]‐naphthalene and [ 14 C 2 ]‐ tert ‐butyl glycinate. Copyright © 2008 John Wiley & Sons, Ltd.