3-(Benzyloxycarbonyl)amino-6-isopropyl-2(1H)-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) δ 8.00 (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.
