General procedure for the synthesis of 4-ethynylaniline from 4-[(trimethylsilyl)ethynyl]aniline: To a stirred solution of potassium hydroxide (1.34 g, 23.8 mmol) in methanol (6 mL) was slowly added a solution of 4-[(trimethylsilyl)ethynyl]aniline (1.10 g, 5.86 mmol) in tetrahydrofuran (5 mL). The reaction mixture was heated to reflux overnight. Upon completion of the reaction, the mixture was cooled to room temperature and filtered to remove insoluble impurities. The filtrate was concentrated under reduced pressure to remove the solvent. The residue was dissolved in dichloromethane (50 mL), filtered and dried using anhydrous magnesium sulfate. The dried solution was concentrated under reduced pressure to give a yellow solid product in 98% yield. The structure of the product was confirmed by nuclear magnetic resonance hydrogen (1H NMR) and carbon (13C NMR) spectra: 1H NMR (400 MHz, CDCl3, Me4Si): δ 7.32 (d, J = 2.4 Hz, 2H), 6.61 (d, J = 2.4 Hz, 2H), 3.83 (s, 2H), 2.98 (s, 1H); 13C NMR (100 MHz, CDCl3): δ 147.0, 133.5, 114.6, 111.3, 84.4, 77.4, 77.1, 76.7, 74.9.
