Synthesis
General procedure for the synthesis of 5-indolinecarbonitrile from 5-cyanoindole: 5-cyanoindole (1 g, 7 mmol) was dissolved in 10 mL of trifluoroacetic acid (TFA) and the solution was cooled to 0 °C. Subsequently, triethylsilane (1.6 g, 14 mmol, 2 equiv) was added to the solution. The reaction mixture was kept stirred at 0 °C for 4 hours. After completion of the reaction, the reaction mixture was diluted with ethyl acetate (EtOAc) and washed with 1 M hydrochloric acid (HCl) solution. The aqueous layers were combined, neutralized to pH 10 with 50% sodium hydroxide (NaOH) solution and then extracted three times with ethyl acetate. The organic extracts were combined, washed with saturated brine, dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure to give the target product 5-indolinecarbonitrile in 77% yield.
References
[1] Patent: US2004/220206, 2004, A1. Location in patent: Page 25-26
[2] Journal of Materials Chemistry A, 2015, vol. 3, # 34, p. 17704 - 17712
[3] Patent: CN105085504, 2018, B. Location in patent: Paragraph 0139; 0147-0150
[4] Patent: WO2014/188173, 2014, A1. Location in patent: Paragraph 00239; 00521
[5] Patent: US2004/220206, 2004, A1. Location in patent: Page 25
