Piperidine → (7S,14S,18S)-tri-tert-butyl 7-amino-1-(1-(2-(bis(2-tert-butoxy-2-oxo ethyl)amino)-2-oxo ethyl)-1H-imidazol-2-yl)-2-((1-(2-(bis(2-tert-butoxy-2-oxo ethyl)amino)-2-oxo ethyl)-1H-imidazol-2-yl)methyl)-8,16-dioxo-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate

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Reaction Steps

To a solution of the above product, (5S,12S,16S)-tri-tert-butyl 5-(4-(bis((1-(2-(bis(2-tert-butoxy-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)methyl)amino)butyl)-1-(9H-fluoren-9-yl)-3,6,14-trioxo-2-oxa-4,7,13,15-tetraazaoctadecane-12,16,18-tricarboxylate in DMF (1.0 mL) was added piperidine (0.50 mL). The mixture was stirred at room temperature for 2 hrs. Solvent was evaporated under reduce pressure to afford a residue, which was purified by biotage eluting with 5% MeOH to 50% MeOH in DCM to afford (7S,14S,18S)-tri-tert-butyl 7-amino-1-(1-(2-(bis(2-tert-butoxy-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)-2-((1-(2-(bis(2-tert-butoxy-2-oxoethyl)amino)-2-oxoethyl)-1H-imidazol-2-yl)methyl)-8,16-dioxo-2,9,15,17-tetraazaicosane-14,18,20-tricarboxylate (40 mg, 25%) as a white solid. 1H NMR (400 MHz, CDCl3) 6.96 (s, 2H), 6.83 (d, 2H), 6.37 (brs, 1H), 6.33 (brs, 1H), 5.05 (s, 4H), 4.87 (brs, 2H), 4.27-4.24 (m, 2H), 4.18 (s, 4H), 4.10 (s, 4H), 3.88 (d, J=15.2 Hz, 2H), 3.62 (d, J=15.2 Hz, 2H), 3.14-3.12 (m, 1H), 2.30-1.24 (m, 83H); MS (ESI), 674.1 (M/2+H)+.

Provenance & Evidence