Selective (~(15)N~eta_2) labelling of an N~G-propionylated arginine derivative

摘要

A straightforward convergent synthesis of [~(15)N~eta_2]-Bz-Arg(N~eta-propionyl)-OEt~*TFA is presented. In this approach, the guanidinylation reagent [~(15)N_2]-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 HgCl_2 to force completion. This method leads directly to the N~G-acylated product and the acyl residue is principally modifiable in the last synthetic step of the guanidinylation reagent.