[C:1]([O:5][CH3:6])(=[O:4])[CH2:2][OH:3].CC(C)=O.C(=O)=O.[H-].[Na+].[N+:16]([C:19]1[CH:20]=[C:21]([CH:24]=[C:25]([N+:27]([O-:29])=[O:28])[CH:26]=1)[CH2:22]Cl)([O-:18])=[O:17]>C1COCC1.C(O)(=O)C>[N+:16]([C:19]1[CH:20]=[C:21]([CH:24]=[C:25]([N+:27]([O-:29])=[O:28])[CH:26]=1)[CH2:22][O:3][CH2:2][C:1]([O:5][CH3:6])=[O:4])([O-:18])=[O:17]
To a solution of methyl glycolate (10 mL, 130 mmol) in THF (50 mL) at -70° C. (acetone-dry ice) was added in small portions, with stirring 60% NaH in oil (1.6 g, 111 mmol). To the resulting white suspension was added a solution of 3,5-dinitrobenzylchloride (5.0 g, 23 mmol). The reaction was allowed to warm to room temperature and acetic acid (2 mL) was added to quench excess NaH. The reaction mixture was concentrated and the residual tan oil was partitioned between water and CH2Cl2. The organic phase was washed with water and dried over Na2SO4. The crude product obtained after concentration was chromatographed on a silica gel column (4×25 cm) eluting with 33% ethyl acetate in hexane. Concentration of appropriate fractions followed by drying in vacuo gave 5.1 g (93%) of the desired product 2.1 as a pale yellow crystalline solid: 1H NMR (CDCl3) δ 8.98 (s, 1H, C4 --H), 8.59 (s, 2H, C2 --H), 4.85 (s, 2H, CH2), 4.29 (s, 2H, CH2), 3.81 (s, 3H, CH3); 13C NMR (CDCl3) δ 170.16, 148.58, 142.33, 127.30, 118.15, 71.10, 68.07, 52.18.
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