Step 2: Synthesis of 5-oxo-5,6,7,8-tetrahydronaphthalene-2-carbonitrile
A solution of 5-oxo-5,6,7,8-tetrahydronaphthalen-2-yl trifluoromethanesulfonate (11.5 g, 39.0 mmol) prepared in the previous step was degassed with zinc cyanide (2.7 g, 23.5 mmol) in anhydrous dimethylformamide (100 mL) and reacted under nitrogen atmosphere. To the reaction mixture was added tetrakis(triphenylphosphine)palladium(0) (1.7 g, 1.5 mmol), which was again degassed and kept under nitrogen atmosphere. The reaction mixture was stirred at 135 °C overnight. Subsequently, tetrakis(triphenylphosphine)palladium (0) (171 mg) was added supplementally and stirring was continued for 4 hours. Upon completion of the reaction, the reaction mixture was filtered through Celite and rinsed with ethyl acetate. The filtrate was washed with water, the organic layer was separated and dried over anhydrous sodium sulfate. The dried organic layer was filtered and concentrated in vacuum to give 8.1 g of crude product. The crude product was purified by silica gel column chromatography using a gradient elution of 5% to 15% ethyl acetate/hexane, resulting in 5-oxo-5,6,7,8-tetrahydronaphthalene-2-carbonitrile (2.8 g, 41% yield) with a mass spectrometry (ES) m/z 172 [M + H]+.
