[C:1]([C:4]1[CH:9]=[CH:8][N:7]([CH3:10])[C:6](=[O:11])[C:5]=1[OH:12])([OH:3])=[O:2].[CH2:13](Cl)[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1.C(=O)([O-])[O-].[K+].[K+]>CN(C)C=O>[CH2:13]([O:12][C:5]1[C:6](=[O:11])[N:7]([CH3:10])[CH:8]=[CH:9][C:4]=1[C:1]([O:3][CH2:13][C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=1)=[O:2])[C:14]1[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=14-Carboxy-1-methyl-3-hydroxy-2(1H)-pyridinone (6.8 g, 0.04 mol) is mixed with benzyl chloride (12.1 g, 0.088 mol), anhydrous potassium carbonate (13.8 g, 0.1 mol) in anhydrous dimethylformamide (DMF) (120 mL). The mixture is heated at 75°-80° C. under N2 in darkness for 16 hours. The reaction mixture is filtered and rotary evaporated to yield a dark oil, which is purified by a silica gel plug as mentioned in the synthesis of 1-methyl-3-hydroxy-2(1H)pyridinone above, to give the 3-benzyloxy-4-benzyloxycarbonyl-1-methyl-2(1H)-pyridinone as a pale yellow, thick oil. It is mixed with methanol (50 mL) and a 6M NaOH solution (10 mL). The mixture is stirred at room temperature for 4 hours, then evaporated to dryness. The residue is dissolved in water (100 mL), and acidified with 6M HCl solution to pH 2 to give the title compound (9.3 g 88.7%), as a white crystalline product, m.p. 152°-153° C. 1H NMR (250 MHz, CDCl3): δ 3.616 (s, 3H), 5.611 (s, 2H), 6.695 (d, 1H, J=7.13), 7.152 (d, 1H, J=7.16), 7.35-7.48 (m, 5H). Anal. for C14H13NO4. 0.2 H2O (262.87), Calcd. (found): C, 63.97 (64.05); H, 5.14 (5.14); N, 5.33 (5.18).
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