General procedure for the synthesis of 4-(furan-2-yl)aniline from 2-furanboronic acid and p-iodoaniline: to a 20 mL Schlenk tube equipped with a magnetic stirrer were added sequentially p-iodoaniline (2 mmol), 2-furanboronic acid (2.4 mmol), K2CO3 (5 mmol), 10 mL of mixed solvents [H2O, H2O-MeOH (1:1), H2O-EtOH (1:1), H2O-EG (1:1)] and 0.01 M palladium catalyst PdCl2(L)2 or Pd[(L)4]Cl2 in MeOH (0.001-0.2 mol%). The reaction mixture was placed in a preheated oil bath and the temperature was set according to the solvent: 100°C for MeOH-H2O, 110°C for EtOH-H2O, 140°C for pure H2O, and 160°C for EG-H2O, and stirred under reflux conditions for the indicated time. Upon completion of the reaction, the mixture was cooled to room temperature, acidified with 5 M HCl (if desired), and subsequently diluted with 10 mL of H2O and 10 mL of Et2O (or EtOAc). The organic phase was separated and the aqueous phase was extracted with Et2O (or EtOAc) (2 x 10 mL). The organic layers were combined and washed sequentially with H2O (10 mL), saturated saline (10 mL) and dried over anhydrous Na2SO4. The ether solution was filtered through a silica gel short column and the filtrate was concentrated under reduced pressure to give pure 4-(furan-2-yl)aniline.
