Synthesis
The general procedure for the synthesis of 6-formylnicotinonitrile from 5-cyano-2-methylpyridine is as follows: a mixed solution of 6-methylnicotinonitrile (10.0 g, 84.6 mmol) and iodine (20.0 g, 78.8 mmol) in dimethylsulfoxide (150 mL) was heated and reacted for 20 min at 150 °C under nitrogen protection (the off-gas generated during the reaction was required to be passed through a bleach washing to remove the dimethyl sulfide). After completion of the reaction, the reaction mixture was cooled to room temperature and slowly neutralized by adding saturated aqueous sodium bicarbonate solution (200 mL). Subsequently, the mixture was extracted with toluene (3 x 100 mL). The organic phases were combined, washed with saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to remove the solvent, yielding the orange oily target product 6-formylnicotinonitrile (5.65 g, 50% yield), which could be used in subsequent reactions without further purification. The structure of the product was confirmed by 1H NMR (CDCl3, 400 MHz): δ 8.06 (1H, d), 8.17 (1H, dd), 9.05 (1H, d), 10.12 (1H, s).
References
[1] Chemical Science, 2015, vol. 7, # 1, p. 346 - 357
[2] Patent: WO2007/96763, 2007, A2. Location in patent: Page/Page column 60
[3] Patent: US2002/19527, 2002, A1
[4] Patent: WO2013/6408, 2013, A1. Location in patent: Page/Page column 43
[5] Bioorganic and Medicinal Chemistry, 2014, vol. 22, # 1, p. 559 - 576
