Sodium Carbonate → 5-Bromo-8-(3,5-dimethoxy-phenyl)-quinoxaline

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A mixture of 3,5-dimethoxyphenylboronic acid (Step 1.8) (3.38 g, 18.6 mmol) in EtOH (15 mL) was added dropwise to a mixture of 5,8-dibromo-quinoxaline (Step 1.5) (10.7 g, 37.1 mmol, 2 equiv), PdCl2(dppf) (530 mg, 0.7 mmol, 0.03 equiv), Na2CO3 (2 M solution in H2O, 37 mL, 74.3 mmol, 4 equiv) in toluene (100 mL) at 105° C., under an argon atmosphere. The reaction mixture was stirred at 105° C. for 2 h, allowed to cool to rt, diluted with EtOAc and H2O, filtered through a pad of celite and extracted with EtOAc. The organic phase was washed with H2O and brine, dried (Na2SO4), filtered and concentrated in vacuo. The crude product was purified by trituration in DCM, followed by silica gel column chromatography (Hex/EtOAc, 4:1) to afford 4.54 g of the title compound as a yellow solid: ES-MS: 345.0 [M+H]+; tR=5.13 min (System 1); Rf=0.17 (Hex/EtOAc, 4:1).

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