Reaction Steps
A solution of ethyl 9-(acetoxymethyl)-9-(chloromethyl)-3-hydroxy-4-oxo-4,6,7,9-tetrahydropyrimido[2,1-c][1,4]oxazine-2-carboxylate (2.05 g, 5.68 mmol) in dimethylfomamide (60 mL) was treated with benzyl bromide (1.46 g, 8.5 mmol, Aldrich) and K2CO3 (1.26 g, 9.1 mmol) and stirred for 16 hrs. Solvent was removed in-vacuo and the crude material was dissolved in ethyl acetate (30 mL) and washed with water (30 mL) and brine (30 mL). The organic solution was dried (Na2SO4), filtered, and concentrated to give an amber oil. This was purified by flash column chromatography, eluting with 5% Et2O in CH2Cl2. Product fractions were pooled and concentrated in-vacuo to give the title compound as a colorless oil: 1H NMR (500 MHz, CDCl3) δ ppm 7.45 (2H, d, J=7.32 Hz), 7.29-7.39 (3H, m), 4.68 (1H, d, J=1 1.90 Hz), 4.37 (1H, d, J=1 1.90 Hz), 4.31 (2H, q, J=7.22 Hz), 4.16-4.24 (2H, m), 4.09-4.16 (1H, m), 4.06 (1H, d, J=11.29 Hz), 3.95-4.03 (1H, m), 3.89 (1H, d, J=1 1.29 Hz), 2.06 (3H, s), 1.56 (2H, s), 1.29 (3H, t, J=7.17 Hz); 13C NMR (126 MHz, CDCl3) δ ppm 170.16, 164.04, 158.67, 150.65, 141.94, 141.67, 136.51, 128.59 128.52, 128.45, 79.57, 74.51, 65.90, 62.11, 60.59, 49.08, 42.16, 20.83, 14.16; HRMS (ESI) calcd for C21H24N2O7Cl (M+H) 451.1272; found 451.1274.
