99902-07-5

1003-09-4

40138-16-7

99902-07-5

In a 100-mL three-neck flask, 3.0 g (20 mmol) of 2-bromothiophene (compound a-1), 4.24 g (26 mmol) of 2-formylphenylboronic acid (compound a-2), 10.6 g (100.0 mmol) of sodium carbonate, 30 mL of toluene, 10 mL of ethanol and 20 mL of water were added. The mixture was stirred at room temperature under the protection of nitrogen atmosphere, followed by the addition of 693 mg of tetrakis(triphenylphosphine)palladium (0). The reaction mixture was heated to 80 °C with continuous stirring for 5 hours. Upon completion of the reaction, the organic layer was extracted with toluene and dried over anhydrous sodium sulfate. Purification by silica gel column chromatography (unfolding agent: toluene/heptane mixture) afforded 3.46 g (92% yield) of the target product 2-thiophene-2-benzaldehyde (Intermediate a-3) as a white oil.