Reaction Steps
To a solution of (S)-2-((((9H-fluoren-9-yl)methoxy)carbonyl)amino)-3-(4-(tert-butoxycarbonyl)phenyl)propanoic acid (0.14 g, 0.29 mmol) in DMF (1.5 mL) was added 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholin-4-ium chloride (86 mg, 0.31 mmol) at rt followed by a solution of (R)-3,3-dimethyl-N—((R)-1,2,3,4-tetrahydronaphthalen-1-yl)-1,3-azasilolidine-5-carboxamide, TFA (105 mg, 0.261 mmol) and DIEA (115 μL) in DMF (2 mL). After 2 h, the reaction mixture was directly purified by preparative HPLC to afford the title compound (165 mg, 83% yield) as a white solid. 1H NMR (400 MHz, CDCl3) δ 7.90 (d, J=8.1 Hz, 2H), 7.75 (d, J=7.5 Hz, 2H), 7.52 (t, J=6.7 Hz, 2H), 7.39-7.06 (m, 10H), 6.51 (d, J=8.4 Hz, 1H), 5.76 (d, J=8.8 Hz, 1H), 5.18-5.00 (m, 3H), 4.38-4.30 (m, 1H), 4.25-4.10 (m, 1H), 3.18 (d, J=13.4 Hz, 1H), 3.08-3.00 (m, 1H), 2.85-2.71 (m, 4H), 2.10-2.02 (m, 1H), 1.91-1.81 (m, 3H), 1.56 (s, 9H), 1.33 (dd, J=14.9, 1.7 Hz, 1H), 1.06 (dd, J=14.7, 10.1 Hz, 1H), 0.46 (s, 3H), 0.29 (s, 3H); MS(ESI+) m/z 758.2 (M+H)+.
