Example 1: (S)-2-(6-(4-chlorophenyl)-8-methoxy-1-methyl-4H-benzo[f][1,2,4]triazolo[4,3-a][1,4]diazepin-4-yl)acetic acid (16.0 g, 40 mmol) was dissolved in THF, N,N-diisopropylethylamine (DIEA, 14 mL, 80 mmol) was added followed by 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU, 30.4 g, 80 mmol) was added. The reaction mixture was stirred at room temperature for 3 h. Then THF solution of ethylamine (40 mL, 2 M, 80 mmol) was added. Stirring was continued for 48 h. The reaction mixture was concentrated under reduced pressure. The crude product was suspended in water and extracted with dichloromethane (DCM). The organic layer was dried with anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (DCM/MeOH, 95:5) and the resulting solid was recrystallized in acetonitrile (MeCN). Subsequently, the solid was dissolved in DCM and precipitated with diisopropyl ether (1-Pr2O) to afford (S)-2-(6-(4-chlorophenyl)-8-methoxy-1-methyl-4H-benzo[f][1,2,4]triazolo[4,3-a][1,4]diazepin-4-yl)-N-ethylacetamide (8 g, 47% yield) as a white solid. rf = 0.48 (DCM/MeOH, 90:10). Melting point >140°C (viscosity change).1H NMR (300 MHz, CDCl3) δ 7.53-7.47 (m, 2H), 7.39 (d, J = 8.9 Hz, 1H), 7.37-7.31 (m, 2H), 7.20 (dd, J = 2.9, 8.9 Hz, 1H), 6.86 (d, J = 2.9 Hz, 1H). 6.40 (m, 1H), 4.62 (m, 1H), 3.80 (s, 3H), 3.51 (dd, J = 7.3, 14.1 Hz, 1H), 3.46-3.21 (m, 3H), 2.62 (s, 3H), 1.19 (t, J = 7.3 Hz, 3H). lc/ms: m/z 424 [M(35Cl)+H]+. Retention time 2.33 min.
