Compound 2a

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Compound data: 1H NMR

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

Iodine (1.1 g, 4.3 mmol) and morpholine (1.0 g, 1 ml, 11.7 mmol) were dissolved in benzene (5 ml) and the solution was stirred at room temperature for 30 min. Phenylacetylene (400 mg, 3.96 mmol) in benzene (5 ml) was added dropwise and the mixture was stirred at 45 °C for 24 h. The suspension was filtered and the residue was washed with Et₂O (2 × 20 ml). The combined organic layers were washed with saturated aqueous solutions of NH₄Cl (20 ml) and NaHCO₃ (20 ml) and H₂O (20 ml). The organic layer was dried over MgSO₄ and filtered. The solvent was removed under reduced pressure and the crude product was purified by column chromatography (silica gel, petroleum ether or n-pentane as eluent) to afford (iodoethynyl)benzene 2a (0.82 g, 3.6 mmol, 92%) as colourless oil. ¹H NMR (400 MHz, CDCl₃) δ 7.43−7.40 (m, 2H), 7.34–7.28 (m, 3H).