A solution of crude [5-[(benzyloxycarbonyl)amino]-2-phenyl-6-oxo-1,6-dihydro-1-pyrimidinyl]acetaldehyde (15.30 g, 42.11 mmol) in 198.0 mL of tetrahydrofuran, t-butyl alcohol, and 2-methyl-2-butene (1:1:1.3, 0.21 M) was cooled to 0° C. The solution was then slowly added a solution of sodium chlorite (29.94 g, 331.1 mmol) and sodium dihydrogenphosphate monohydrate (35.42 g, 256.7 mmol) in 102.0 mL of water (3.2 M based on sodium chlorite). The resulting gold colored, biphasic solution was stirred for 10 minutes and the cold bath was removed. The reaction was stirred for 1 hour at room temperature. The volatiles were removed under reduced pressure. The resulting solution was diluted with water (200 mL) and the pH was adjusted to 3 by addition of sat NaHCO3 and 1 N HCl. The aqueous solution was extracted by tetrahydrofuran, dichloromethane (1:2, 4×180 mL). The combined organic solutions were dried (MgSO4), filtered, and concentrated to give the crude product. Purification by trituration with ethyl ether gave an 88% yield of [5-[(benzyloxycarbonyl)amino]-2-phenyl-6-oxo-1,6-dihydro 1-pyrimidinyl]acetic acid as a white solid: 1H NMR (300 MHz, d-DMSO) δ 13.34 (br s, 1H), 9.03 (s, 1H), 7.57-7.34 (m, 10H), 5.23 (s, 2H), 4.56 (s, 2H); 13C NMR (75 MHz, d-DMSO) δ 169.4, 158.0, 154.6, 154.3, 137.1, 134.8, 130.9, 129.4, 129.1, 128.78, 128.72, 128.50, 125.5, 67.0, 48.8; HRMS (EI) calcd for C20H18N3O5 380.1246, found 380.1246.
