Diisopropylethylamine → methyl ((S)-1-((S)-2-(5-(4'-(2-((S)-1-((S)-2-amino-3-methylbutanoyl)pyrrolidin-2-yl)-1H-imidazol-4-yl)-[1,1'-biphenyl]-4-yl)-1H-imidazol-2-yl)pyrrolidin-1-yl)-3-methyl-1-oxobutan-2-yl)carbamate

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Reaction Steps

To a solution of methyl(S)-3-methyl-1-oxo-1-((S)-2-(5-(4′-(2-((S)-pyrrolidin-2-yl)-1H-imidazol-5-yl)biphenyl-4-yl)-1H-imidazol-2-yl)pyrrolidin-1-yl)butan-2-ylcarbamate (cj-12) (1.16 g, 1.99 mmol), Z-Val-OH (0.712 g, 2.83 mmol) and iPr2NEt (0.70 mL, 5.42 mmol) in DMF (40 mL) was added HATU (1.10 g, 2.89 mmol) portionwise. The mixture was allowed to stir at room temperature for 1 h and was then poured into ice-water (400 mL) and allowed to stand for 20 min. The mixture was filtered and the solid washed with cold water and allowed to air dry overnight to give the Z-protected intermediate. LCMS: Anal. Calcd. for C46H54N8O6: 814. found: 815 (M+H)+. The obtained solid was dissolved in MeOH (80 mL), 10% Pd—C (1.0 g) was added and the mixture was hydrogenated at room temperature and atmospheric pressure for 3 h. The mixture was then filtered and the filtrate concentrated in vacuo. The resulting residue was purified by flash chromatography (SiO2/5-20% MeOH—CH2Cl2) to afford the title compound (1.05 g, 77%) as a colorless foam. 1HNMR (400 MHz, DMSO-d6) δ 11.75 (s, 1H), 7.75-7.79 (m, 3H), 7.61-7.67 (m, 5H), 7.49 (s, 1H), 7.26-7.28 (m, 1H), 5.05-5.09 (m, 2H), 4.03-4.09 (m, 2H), 3.77-3.80 (m, 1H), 3.66-3.70 (m, 1H), 3.52 (s, 3H), 3.40-3.47 (m, 2H), 2.21-2.26 (m, 1H), 2.10-2.17 (m, 3H), 1.81-2.02 (m, 6H), 0.77-0.92 (m, 12H). LCMS: Anal. Calcd. for C38H48N8O4: 680. found: 681 (M+H)+.

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