(S)-2-tert-Butoxycarbonylamino-3-(4-hydroxy-phenyl)-propionic acid methyl ester (8.46 mmol), 4-pyridyl boronic acid (29.6 mmol), Cu(OAc)2 (16.9 mmol), and molecular sieves were suspended in 25 mL of DCM. Triethylamine (59.2 mmol) was added and the mixture stirred at rt for 10 h. The mixture was diluted with ethyl acetate and washed with 10% sodium carbonate (6×). The organic layer was dried and concentrated under reduced pressure. The residue was purified over silica gel (hexanes-EtOAc) to provide (S)-2-tert-Butoxycarbonylamino-3-[4-(pyridin-4-yloxy)-phenyl]-propionic acid methyl ester (653 mg). LC-MS (m/z) 374.
