Procedure for the synthesis of 6-acetylnicotinonitrile: The crude 6-(1-ethoxyvinyl)nicotinonitrile (14.5 g, purity about 80%) was dissolved in a mixed solution of THF (120 mL) and 2.5 N hydrochloric acid (40 mL). The reaction solution was stirred continuously for 16 hours at room temperature. Upon completion of the reaction, the pH of the reaction solution was adjusted to 7.5 with saturated aqueous NaHCO3 to quench the reaction. Subsequently, the reaction mixture was extracted with EtOAc (200 mL). The organic layer was dried with Na2SO4, filtered and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (120 g silica gel), and the eluent was hexane/EtOAc (gradient ratio from 9:1 to 3:1), which ultimately yielded the target intermediate 6-acetylnicotinonitrile (4.2 g, 65% yield).
