Intermediate B (114 mg, 0.39 mmol) and N-methylpiperazine (2 mmol, 6 eq, 204 mg, 0.22 mL) in 1 mL of DMSO was heated at 120° C. in a microwave for 2 h. The reaction was diluted with water and extracted with EtOAc. The organic extracts were washed 5× with water, then dried with MgSO4 and evaporated. The residue was purified by reverse-phase HPLC (eluting with 10-30% acetonitrile in water with 0.1% TFA over 20 min; Phenomenex Luna C-18 column, 25×2 cm) to give the title compound after lyophylization. LCMS: 359.2 m/z (M+H)+; ret. Time: 6.72 min (Analytical Method A); 1H NMR (400 MHz, CDCl3) δ: 7.6 (s, 1H), 4.3 (ddd, 1H), 4.1 (dd, 1H), 4.8 (broad s, 4H), 3.3 (s, 3H), 2.5 (broad s, 4H), 2.3 (s, 3H), 2.1-1.6 (m, 10H) and 0.9 ppm (dd, 3H).
