A mixture of 2-bromo-5-(2-trimethylsilanyl-ethoxymethyl)-5H-pyrrolo[2,3-b]pyrazine-7-carbaldehyde (3.29 g, 9.23 mmol), phenol (1.04 g, 11.08 mmol), K3PO4 (3.92 g, 18.46 mmol), [2′-(di-tert-butyl-phosphanyl)-biphenyl-2-yl]-dimethyl-amine (0.157 g, 0.46 mmol), Pd(OAc)2 (0.103 g, 0.46 mmol) and degassed toluene (50 mL) was stirred under nitrogen in a sealed tube at 150° C. overnight. The reaction mixture was cooled to room temperature and partitioned between ethyl acetate and water. The aqueous layer was extracted with ethyl acetate, and the combined organic layers were dried over MgSO4, filtered and concentrated. The residue was purified by SiO2 column chromatography (0-30% EtOAc/hexanes) to afford 2.09 g (61%) of 2-phenoxy-5-(2-trimethylsilanyl-ethoxymethyl)-5H-pyrrolo[2,3-b]pyrazine-7-carbaldehyde as a beige solid.
