Short-RInChIKey=SA-FUHFF-UHFFFADPSC-VYVOWDOXIR-UHFFFADPSC-NUHFF-OCUED-NUHFF-ZZZ

The synthesis of the starting material was performed following: https://www.chemotion-repository.net/pid/17397(3S,6S)-3-((1H-indol-3-yl)methyl)-6-(4-aminobutyl)-1,10-dibenzyl-1,4,7,10-tetraazacyclododecane-2,5,8,11-tetraone (5.00 mg, 8.21 μmol, 1.00 equiv), [9-(2-carboxyphenyl)-6-(diethylamino)xanthen-3-ylidene]-diethyl-azanium (5.46 mg, 12.3 μmol, 1.50 equiv), [dimethylamino(triazolo[4,5-b]pyridin-3-yloxy)methylidene]-dimethylazanium;hexafluorophosphate (4.68 mg, 12.3 μmol, 1.50 equiv) and N-ethyl-N-propan-2-ylpropan-2-amine (8.49 mg, 11.4 μL, 65.7 μmol, 8.00 equiv) were dissolved in 5 mL of dimethylformamide. The reaction mixture was stirred for 3 d at 21 °C.The solvent was removed under reduced pressure and the residue was dissolved in a mixture acetonitrile and water.