Uses
2-Ethynylbenzaldehyde may be used in the synthesis of the following:
- iodoisoquinoline-fused benzimidazoles obtained via tandem iodocyclization of 2-ethynylbenzaldehyde with o-benzenediamine and iodine in the presence of copper(I)iodide
- N-[(7,7a-dihydroisoquinolino[2,1-a]perimidin-13-yl)methyl]-N-isopropylpropan-2-amine obtained via a multi-step process
It may also be used in the synthesis of the following substituted 2-alkynylbenzaldehydes by Sonogashira coupling:
- 2-[(2-bromophenyl)ethynyl]benzaldehyde
- 2-[(2-bromo-5-fluorophenyl)ethynyl]benzaldehyde
- 2-[(2-bromo-5-methylphenyl)ethynyl]benzaldehyde
- 2-(phenylethynyl)benzaldehyde
- 2-[(4-methylphenyl)ethynyl]benzaldehyde
Synthesis
General procedure for the synthesis of 2-ethynylbenzaldehyde from 2-[(trimethylmethylsilyl)ethynyl]benzaldehyde: 2-[(trimethylmethylsilyl)ethynyl]benzaldehyde (1 mmol), an inorganic base (potassium tert-butanol, sodium tert-butanol, potassium hydroxide, sodium hydroxide, or potassium trimethylmethylsilyl, sodium trimethylmethylsilyl, 0.05 mmol), and 2 mL of DMA or DMSO solvent were added to a 10mL sealed tube. The mixture was placed in an oil bath at 60 °C and the reaction was stirred for 12 h. The progress of the reaction was monitored by TLC. Upon completion of the reaction, equal amounts of homotrimethylbenzene or n-undecane were added as an internal standard for the crude product, and the exact yield of the product was determined by GC and GC-MS analysis. According to the results of GC and GC-MS analyses, when DMSO was used as the reaction solvent and potassium tert-butanol, sodium tert-butanol, potassium hydroxide, sodium hydroxide, or potassium trimethylmethylsilyl, sodium trimethylmethylsilyl were used as catalysts, the yields of the products were 44%, 47%, 49%, 50%, 77%, and 70% respectively. When DMA was used as the reaction solvent with the same inorganic base as the catalyst, the yields of the products were 40%, 42%, 42%, 40%, 61%, 59%, respectively.
References
[1] Synthesis, 2010, # 14, p. 2367 - 2378
[2] European Journal of Organic Chemistry, 2017, vol. 2017, # 11, p. 1425 - 1433
[3] Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999), 1987, p. 2321 - 2332
[4] Advanced Synthesis and Catalysis, 2011, vol. 353, # 2-3, p. 392 - 400
[5] Journal of the American Chemical Society, 2015, vol. 137, # 9, p. 3233 - 3236
