Cl[C:2]1[N:9]=[CH:8][CH:7]=[CH:6][C:3]=1[C:4]#[N:5].C(N(CC)CC)C.[C:17]([Si:19]([CH3:22])([CH3:21])[CH3:20])#[CH:18].O>C1(C)C=CC=CC=1.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.C1C=CC(P(C2C=CC=CC=2)[C-]2C=CC=C2)=CC=1.Cl[Pd]Cl.[Fe+2].[Cu]I>[CH3:20][Si:19]([C:17]#[C:18][C:2]1[N:9]=[CH:8][CH:7]=[CH:6][C:3]=1[C:4]#[N:5])([CH3:22])[CH3:21]
To a solution of 2-chloronicotinonitrile (21.6 g, 156 mmol) in toluene (200 mL) was added Pd(dppf)Cl2 (2.3 g, 3.12 mmol), copper (I) iodide (594 mg, 3.12 mmol), triethylamine (32 mL, 312 mmol) and ethynyltrimethylsilane (23 g, 234 mmol). The reaction mixture was stirred at 70° C. under N2 for 5 h. The reaction mixture was filtered through a Celite pad. The filtrate was concentrated under reduced pressure to give a residue. 40 mL of water was added to the residue, and the mixture was extracted with EtOAc (3×100 mL). The combined organic layers were washed with brine (1×100 mL), dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (eluting with a gradient of PE/EtOAc v/v 40:1, 20:1, 10:1, 5:1) to yield 2-((trimethylsilyl)ethynyl)nicotinonitrile as a yellow solid (19.14 g, yield 61%). ESI MS: m/z 201 [M+H]+.
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