4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenylamine (1.34 g, 6.104 mmol, 1 equiv.) and 2-(4-Bromo-benzoylamino)-pentanedioic acid di-tert-butyl ester (2.7 g, 6.104 mmol, 1 equiv.) were dissolved in DME (120 mL). A solution of K2CO3 (1.68 g, 12.21 mmol, 2 equiv.) in 30 mL of water was injected into the mixture, followed by the addition of Pd(PPh3)4 (352 mg, 0.31 mmol, 5%). The mixture was heated to reflux overnight. Reaction was complete as determined by TLC. Regular work-up and column chromatography (silica gel, 30-40% EtOAc/n-Hexane) afforded 2.3 g of 2-[(4′-Amino-biphenyl-4-carbonyl)-amino]-pentanedioic acid di-tert-butyl ester in 83% yield. MS (ESI) m/z 453.
