A mixture of 3,5-dimethoxyphenylboronic acid (15.1 g, 82.7 mmol, 1.1 equiv) (Step 1.8) in EtOH (50 mL) was added dropwise to a mixture of 3,6-dibromo-benzene-1,2-diamine (20 g, 75.2 mmol) (Step 1.6), PdCl2(dppf) (6.1 g, 7.5 mmol, 0.1 equiv), Na2CO3 (2 M solution in H2O, 150 mL, 300.8 mmol, 4 equiv) in toluene (300 mL) at 105° C., under an argon atmosphere. The reaction mixture was stirred at 105° C. for 3 h, allowed to cool to rt, diluted with EtOAc and H2O and extracted with EtOAc. The organic phase was washed with H2O and brine, dried (Na2SO4), filtered and concentrated. The crude product was purified by silica gel column chromatography (DCM) followed by trituration in EtOH to afford 9.2 g of the title compound as a white solid: ES-MS: 323.0/325.0 [M+H]+; tR=4.43 min (System 1); Rf=0.15 (DCM).
