Synthesis
General procedure for the synthesis of ethyl 5-cyano-1H-indole-2-carboxylate: a suspension of cuprous cyanide (27 mg, 0.3 mmol) and ethyl 5-bromoindole-2-carboxylate (138) in 500 μL of DMF was stirred and reacted for 7 hours at 155 °C. After completion of the reaction, it was purified by silica gel column chromatography (3 × 15 cm, SiO, 20% EtOAc/hexane as eluent) to afford the target product, ethyl 5-cyano-1H-indole-2-carboxylate (139) (34 mg, 63% yield), as a white solid with melting point of 181-182 °C.
