Synthesis
To a solution of 4-bromobenzaldehyde (3.70 g, 20.0 mmol), cuprous iodide (CuI, 380 mg, 2.00 mmol) and tetrakis(triphenylphosphine)palladium (Pd(PPh3)4, 924 mg, 800 μmol) in tetrahydrofuran (THF, 60 mL) was added triethylamine (Et3N, 11.2 mL, 80.3 mmol) and tris methylsilylacetylene (4.24 mL, 30.0 mmol). The reaction mixture was stirred at room temperature under argon (Ar) protection overnight, followed by filtration and washing of the solid with ethyl acetate (EtOAc, 30 mL). The filtrate and washings were combined and concentrated under reduced pressure, and the residue was purified by fast column chromatography (silica gel, petroleum ether, gradient elution to petroleum ether:EtOAc = 98:2) to afford 4-((trimethylsilyl)ethynyl)benzaldehyde as a light brown solid (4.04 g, 100%). Thin layer chromatography (TLC) Rf value (petroleum ether:EtOAc = 4:1) was 0.87. The melting point was 66-67°C (literature [7] reported a melting point of 70°C). Infrared spectra (IR) νmax/cm-1: 2960, 2899, 2832, 2733, 2159, 1702, 1600, 1563, 1412, 1384, 1303, 1251, 1205, 1165, 862, 842.1H NMR (300 MHz, CDCl3) δ: 0.19 (s, 9H, Si( CH3)3), 7.47 (d, 2H, J = 8.1 Hz, Ph-H), 7.68 (d, 2H, J = 7.8 Hz, Ph-H), 9.87 (s, 1H, CHO).13C NMR (75 MHz, CDCl3) δ: 0.3, 98.8, 103.8, 129.1, 129.3, 132.3, 135.5, 191.0 (four carbon signals overlapped or blurred). Mass spectra (MS, GC-EI): 187.1 ([M-CH3]+, 100%), 202.0 (M+, 8%). The spectral data are in agreement with those reported in the literature [7].
References
[1] Advanced Synthesis and Catalysis, 2006, vol. 348, # 15, p. 2101 - 2113
[2] Beilstein Journal of Organic Chemistry, 2014, vol. 11, p. 37 - 41
[3] PLoS ONE, 2015, vol. 10, # 6,
[4] Chemistry - A European Journal, 2010, vol. 16, # 25, p. 7389 - 7394
[5] Chemical Communications, 2011, vol. 47, # 4, p. 1282 - 1284
