A solution of m-guanidinohippuric acid HCl (1.5 g) in DMF (4.5 ml) and pyridine (4.5 ml) was treated with DSC (1.8 g) and a catalytic amount of DMAP. After 2 hours, a solution of-dimethyl 3-aminoglutarate HCl (1.1 g) and NMM (350 μl) in H2O (3 ml) was added to the reaction. The reaction was stirred overnight at room temperature and the product was isolated by HPLC. 3-[[2-[[[3-[(aminoiminomethyl)amino]phenyl]carbonyl]-amino]acetyl]amino]pentanedioic acid, bis methyl ester (1.5 g) as a white solid was obtained. MS and 1H-NMR were consistent with the desired product.
