The solution of crude dimethyl[5-(benzyloxy)-1-(biphenyl-3-yl)-4-oxo-1,4-dihydropyridin-3-yl]boronate (2.4 mmol) in THF/MeOH from the preceeding step and 10% Pd/C (52 mg, 0.49 mmol) was stirred under H2 (1 atm) for 18 h. The reaction mixture was diluted with MeOH (20 mL), filtered through a pad of Celite (MeOH wash), and concentrated under reduced pressure, The residue was diluted with DMF (10 mL) and 0.5 M aq, HCl (0.4 mL) and purified by reversed phase HPLC (2 cm×5 cm C18, acetonitrile-water gradient, 0.05% TFA added, fractions were lyopholized) to provide [1-(biphenyl-3-yl)-5-hydroxy-4-oxo-1,4-dihydropyridin-3-yl]boronic acid. ′H NMR (599 MHz, DMSO, 75° C.): S 8.19 (d, J=2.3 Hz, 1H); 7.89 (d, J=2.3 Hz, 1H); 7.83 (s, 1H); 7.79-7.74 (m, 3H); 7.67-7.61 (m, 1H); 7.56 (d, J=8.1 Hz, 1H); 7.49 (t, J Hz, 2H); 7.46-7.38 (m, 1H). HRMS (ES) calc (M+H)+ −308.1089. found 308.1092.
