To a stirred solution of 5-bromothiophene-2-carbaldehyde (1 g, 5.2 mmol) in toluene (40 mL) and ethanol (20 mL) was added (4-methoxyphenyl)boronic acid (1.59 g, 10.4 mmol), 2M Na2CO3 (14.7 mL), and Pd(PPh3)4 (60 mg, 0.05 mmol). The reaction was purged with argon and heated at 60° C. for about 5 h. The reaction mixture was concentrated, diluted with water (100 mL), and extracted with ethyl acetate (2×200 mL). The combined organic extracts were washed with brine solution (20 mL), the organic layer was dried over Na2SO4 and concentrated under vacuum to obtain crude product. The crude product was purified by flash chromatography (silica gel, 60-120μ) using 10% ethyl acetate in hexane eluent to afford 5-(4-methoxyphenyl)thiophene-2-carbaldehyde as off white solid (1 g, 87.7% yield). 1H NMR (400 MHz, DMSO-d6): δ 9.85 (s, 1H), 7.97 (d, 1H), 7.73 (d, 2H), 7.61 (d, 1H), 7.02 (d, 2H), 3.98 (s, 3H); LC-MS m/z calcd for [M+H]+ 219.04. found 219.3.
