Synthesis
To a dichloromethane solution of CBr4 (9.70 g, 29.4 mmol) was slowly added a dichloromethane solution of PPh3 (15.4 g, 58.8 mmol) at 0 °C. After stirring for 5 min, m-anisaldehyde (1.99 g, 14.6 mmol) was added to the reaction system and stirring was continued for 20 min. After completion of the reaction, water and dichloromethane were added for dilution. The organic layer was separated, washed sequentially with saturated NaHCO3 solution and brine, dried over anhydrous MgSO4 and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane) to afford 2',2'-dibromo vinyl-3-methoxybenzene (2.00 g, 6.80 mmol, 92% yield) as a colorless oil.1H NMR (CDCl3, 400 MHz) data were as follows: δ= 3.82 (s, 3H), 6.91 (dd, 1H, J = 8.2, 2.3 Hz) , 7.12 (d, 1H, J = 8.2 Hz), 7.15 (d, 1H, J = 2.3 Hz), 7.29 (t, 1H, J = 8.2 Hz), 7.48 (s, 1H). To a tetrahydrofuran solution of 3-(2',2'-dibromovinyl)methoxybenzene (1.80 g, 6.20 mmol) was added dropwise n-butyllithium (2.6 M hexane solution; 5.00 ml, 13.0 mmol) at -78 °C. After stirring for 15 minutes, the reaction was quenched by the addition of saturated NH4Cl solution and the reaction mixture was slowly warmed to room temperature. The mixture was extracted with ether, the organic layers were combined, washed sequentially with saturated NaHCO3 solution and brine, dried over anhydrous MgSO4 and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane/ethyl acetate=10:1) to afford 3-ethynyl anisole (472 mg, 3.57 mmol, 58% yield) as a colorless oil.
References
[1] Tetrahedron Letters, 2011, vol. 52, # 9, p. 992 - 994
[2] Organic Letters, 2009, vol. 11, # 1, p. 229 - 231
[3] Advanced Synthesis and Catalysis, 2015, vol. 357, # 2-3, p. 553 - 560
[4] Bioorganic and Medicinal Chemistry Letters, 2015, vol. 25, # 22, p. 5127 - 5132
[5] Heterocyclic Communications, 2016, vol. 22, # 3, p. 165 - 167
