With copper(l) iodide; In N,N-dimethyl-formamide; at 100℃; for 34h;
General procedure: A mixture of CuI (0.6 mmol), indoles (0.5 mmol) and benzyl cyanide (0.6 mmol) in DMF (3.0 mL) was stirred under air at 100 C for 34 h and then cooled to room temperature. After the reaction mixture was quenched with 10 mL of water, it was extracted with DCM (3×10 mL). The combined organic layers were washed with the saturated aqueous solution of sodium chloride and dried over MgSO4. The solution was concentrated under reduced pressure and purified by column chromatography to afford 3-cyanoindoles.