(14S,18S)-tri-tert-butyl 1-(1-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-((1-(3-(2-(4,7,10-tris(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)propyl)-1H-1,2,3-triazol-4-yl)methoxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate → (14S,18S)-1-(1-(2-(bis(carboxymethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-((1-(3-(2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)propyl)-1H-1,2,3-triazol-4-yl)methoxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylic acid

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Reaction Steps

A solution of ((14S,18S)-tri-tert-butyl 1-(1-(2-(bis(2-(tert-butoxy)-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-((1-(3-(2-(4,7,10-tris(2-(tert-butoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)propyl)-1H-1,2,3-triazol-4-yl)methoxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate (21 mg, 0.012 mmol) in TFA (2.0 mL) and DCM (2.0 mL) was stirred at rt overnight. The solvent was removed under a stream of nitrogen to give a crude ((14S,18S)-1-(1-(2-(bis(carboxymethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-8,16-dioxo-2-(4-((1-(3-(2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)propyl)-1H-1,2,3-triazol-4-yl)methoxy)benzyl)-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylic acid, (MIP-1459), which was dissolved in ammonium acetate (0.30 mL, 0.50 N) solution in water (0.50 mL) with InCl3 (10 mg). The reaction mixture was heated at 95° C. for 1 h and was purified by HPLC to give the product (MIP-1445, (1 mg)). MS (ESI), 714.9 (M/2+H)+.

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