Synthesis
GENERAL PROCEDURE: To a solution of 4-nitroaniline (0.5 mmol, 1.0 eq.) in methanol (1.0 mL) was added hydrochloric acid (0.5 mL, 1.5 mmol, 3.0 eq.) followed by water (0.5 mL). The mixture was stirred for 2 minutes and then sodium nitrite solution (0.25 mL) was added. Sodium nitrite solution was prepared by dissolving 35 mg of sodium nitrite in water (0.25 mL). The reaction mixture was stirred at 0-5 °C for 30 min, followed by the addition of a methanol (1.0 mL) solution of pinacol ester of bisboronic acid (2,381 mg, 1.5 mmol, 3.0 equiv). Stirring was continued for 60 minutes. Upon completion of the reaction, water (10 mL) was added to the mixture, which was then extracted with dichloromethane (50 mL, 3 times). The organic layers were combined and washed with saturated sodium bicarbonate solution followed by drying with anhydrous sodium sulfate. After drying, the solvent was evaporated and the crude product was purified by fast chromatography.
References
[1] Synlett, 2014, vol. 25, # 11, p. 1577 - 1584
[2] Angewandte Chemie - International Edition, 2010, vol. 49, # 10, p. 1846 - 1849
[3] Angewandte Chemie - International Edition, 2010, vol. 49, # 10, p. 1846 - 1849
[4] Tetrahedron Letters, 2016, vol. 57, # 14, p. 1551 - 1554
[5] Synlett, 2012, vol. 23, # 9, p. 1394 - 1396
