Diisopropylethylamine → (2S,7S,11S)-2-(4-(bis((1-(2-tert-butoxy-2-oxoethyl)-1H-imidazol-2-yl)methyl)amino)butyl)-7,11-bis(tert-butoxycarbonyl)-16,16-dimethyl-4,9,14-trioxo-15-oxa-3,8,10-triazaheptadecan-1-oic acid

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Reaction Steps

A solution of (S)-di-tert-butyl 2-(3-((S)-1-tert-butoxy-5-(2,5-dioxopyrrolidin-1-yloxy)-1,5-dioxopentan-2-yl)ureido)pentanedioate (138 mg, 0.236 mmol), (S)-2-amino-6-(bis((1-(2-tert-butoxy-2-oxoethyl)-1H-imidazol-2-yl)methyl)amino)hexanoic acid (127 mg, 0.237 mmol) and DIPEA (0.50 mL) in DMF (1.0 mL) was stirred at rt for overnight. The Solvent was removed under reduced pressure to give a residue, which was purified by biotage eluting with 1% to 50% MeOH in DCM to afford (2S,7S,11S)-2-(4-(bis((1-(2-tert-butoxy-2-oxoethyl)-1H-imidazol-2-yl)methyl)amino)butyl)-7,11-bis(tert-butoxycarbonyl)-16,16-dimethyl-4,9,14-trioxo-15-oxa-3,8,10-triazaheptadecan-1-oic acid (203 mg, 86%) as a white solid. 1H NMR (400 MHz, CDCl3) 7.40 (brs, 1H), 6.99 (s, 2H), 6.79 (s, 2H), 6.12 (brs, 1H), 5.62 (brs, 1H), 4.67-4.28 (m, 7H), 3.68 (d, J=14.0 Hz, 2H), 3.62 (d, J=14.0 Hz, 2H), 2.62-2.53 (m, 2H), 2.34-2.02 (m, 8H), 1.83-1.42 (m, 51H); MS (ESI), 503.5 (M/2H)+.

Provenance & Evidence