3-(Benzyloxycarbonyl)amino-6-isopropyl-2(1 H)-pyridinone (1.10 g, 3.84 mmol), as prepared in the preceding step, was dissolved in anhydrous tetrahydrofuran (30 mL) and cooled to 0° C. under nitrogen. A 1.0 M solution of lithium bis(trimethylsilyl)amide in hexanes (4.2 mL, 4.2 mmol) was added via syringe and the reaction stirred for one hour. tert-Butylbromoacetate (0.70 mL, 4.3 mmol) was then added via syringe and the reaction stirred at ambient temperature for 16 hours. After concentration in vacuo, the crude product was purified by flash column chromatography (1:1 hexane:ethyl acetate) giving the title compound as a pale yellow oil (1.38 g, 90%). 1H NMR (300 MHz, CDCl3) δ8.00 (br d, 1H, J=7.8 Hz), 7.78 (s, 1H), 7.36 (m, 5H), 6.15 (d, 1H, J=7.9 Hz), 5.19 (s, 2H), 4.79 (s, 2H), 2.72 (m, 1H), 1.46 (s, 9H), 1.26 (s, 3H), 1.23 (s, 3H). Mass spectrum (MALDI-TOF, gentisic acid matrix) calcd. for C22H28N2O5: 423.2 (M+Na). Found: 423.6.
