Synthesis
A reaction mixture was prepared using 4-methoxyphenylboronic acid (1 g, 6.58 mmol) and 4-iodobenzoic acid (1.63 g, 6.58 mmol) as raw materials and cesium carbonate (5.36 g, 16.45 mmol) as base in a 3:1 solvent mixture of 1,2-dimethoxyethane/water. The reaction system was degassed with nitrogen for 15 min and then tetrakis(triphenylphosphine)palladium (380 mg, 0.329 mmol) was added as catalyst. The reaction mixture was heated to 80 °C and the reaction was stirred at this temperature for 6 hours. Upon completion of the reaction, it was cooled to room temperature and acidified with 2M hydrochloric acid to pH<7, at which point a precipitate was generated. The precipitate was collected by filtration and the filtrate was extracted twice with dichloromethane. The organic layers were combined, dried with anhydrous magnesium sulfate, filtered through diatomaceous earth and concentrated under reduced pressure to give 1.50 g of 4'-methoxybiphenyl-4-carboxylic acid in 95% yield. The product was characterized by 1H NMR (DMSO-d6) and 13C NMR (DMSO-d6) with the following data: 1H NMR (DMSO-d6): δ 7.99 (d, J = 8.4 Hz, 2H), 7.74 (d, J = 8.4 Hz, 2H), 7.69 (d, J = 8.7 Hz, 2H), 7.04 (d, J = 8.7 Hz, 2H), 7.04 (d, J = 8.7 Hz, 2H), 3.80 (d, J = 8.7 Hz, 3.80 (d, J = 8.7 Hz, 2H), 4.50g of 4'-methoxybiphenyl-4-carboxylic acid. 2H), 3.80 (s, 3H); 13C NMR (DMSO-d6): δ 167.17, 159.49, 143.90, 131.16, 129.91, 128.77, 128.09, 126.08, 114.45, 55.17.
References
[1] Russian Chemical Bulletin, 2007, vol. 56, # 2, p. 369 - 370
[2] Green Chemistry, 2010, vol. 12, # 1, p. 150 - 158
[3] Patent: WO2009/146013, 2009, A1. Location in patent: Page/Page column 52
[4] Green Chemistry, 2009, vol. 11, # 12, p. 1929 - 1932
[5] Tetrahedron, 2012, vol. 68, # 32, p. 6517 - 6520
