Selective [15N.eta.2] labelling of an NG-propionylated arginine derivative

Abstract

A straightforward convergent synthesis of [15N[stack 2 ]]-Bz-Arg(N-propionyl)-OEt*TFA is presented. In this approach, the guanidinylation reagent [15N2]-N(boc)-N(propionyl)-S-methylisothiourea is reacted with the side chain amino group of the title compound's ornithine precursor. The guanidinylation step is promoted by stoichiometric addition of HgCl2 to force completion. This method leads directly to the NG-acylated product and the acyl residue is principally modifiable in the last synthetic step of the guanidinylation reagent.