N-tert-butoxycarbonyl cadaverine (24.3 mg; 0.12 mmol) was added to a solution of 17-((S)-1-Carboxy-3-{2-[2-({2-[2-(2,5-dioxo-pyrrolidin-1-yloxycarbonyl methoxy)ethoxy]ethylcarbamoyl}methoxy)ethoxy]ethylcarbamoyl}propylcarbamoyl)-heptadecanoic acid (100 mg; 0.12 mmol) and DIPEA (46.68 mg; 0.36 mmol) in THF (2.0 ml). Reaction mixture was stirred over night at room temperature, and then concentrated in vacuo. The residue was dissolved in a mixture of water (5 ml) and THF (2 ml), and purified by preparative HPLC (RP18 column). Fractions containing the Boc-protected coupling product was pooled and taken to dryness. The residual was dissolved in 50% TFA-DCM (4 ml) and stirred for 1 h at room temperature, then concentrated in vacuo to provide 54 mg (55%) of the title material as its trifluoroacetic acid salt.
