Cyclooctylamine (24 mg, 0.19 mmol) was added to a suspension of compound 1 (0.05 g, 0.16 mmol), WSC (37 mg, 0.19 mmol), HOBt (29 mg, 0.19 mmol) and DMAP (23 mg, 0.19 mmol) in DMF (1.5 mL). The reaction mixture was stirred at room temperature for 14 h, diluted with DCM (0.5 mL) and saturated NaHCO3 solution (0.5 mL), and then separated using PHASE-SEP filtration syringe. The organic layer was concentrated and loaded onto preparative HPLC (Gilson 215 system). The purest fractions were combined to give 64.6 mg (96% yield) of the title compound as a white solid. Reverse Phase LC/MS: CAPCELLPAKCC18UG120, S-3 μm, 2.0×50 mm, UV detection at 220, 8 min. gradient 10-100% Solvent B/A (Solvent A: CH3CN with 0.1% TFA, Solvent B: H2O with 0.1% TFA), 0.5 mL/min. Rt=1.90 min, (96% pure). MS (M+H: 421).
