A mixture of 7-bromo-1,4-diisopropyl-6-methyl-1,2,3,4-tetrahydroquinoxaline (469 mg, 1.51 mmol), 2-methoxy-5-formylphenylboronic acid (407 mg, 2.26 mmol), potassium carbonate (834 mg, 6.03 mmol) and water (2.5 mL) in anhydrous 1,2-dimethoxyethane (30 mL) was degassed with argon for 15 minutes prior to the addition of tetrakis(triphenylphosphine)palladium (0) (349 mg, 0.30 mmol). The reaction mixture was heated under reflux for 8.5 hours, allowed to cool to room temperature and extracted with ethyl acetate (2×100 mL). The organic extracts were successively washed with water (100 mL), saturated aqueous NH4Cl (100 mL), saturated aqueous NaCl (100 mL), dried over MgSO4 and filtered. Removal of the solvent under reduced pressure gave an oil which was purified by column chromatography, using a Biotage 40S cartridge, eluting with 10% ethyl acetate/90% hexane. The title compound was isolated as bright yellow solid (315 mg, 57%).
