反应详情

Oxalyl chloride (9.22 g, 6.4 mL, 72.6 mmol, 1.1 eq) and DMF (cat) were added to a suspension of 4,5-dimethoxy-2-nitrobenzoic acid (1, 15.0 g, 66 mmol) in anhydrous CH2Cl2 (150 mL) under a N2 atmosphere. The suspension was stirred at room temperature for 18 hours. The resultant solution was added dropwise to a solution of (S)-(+)-2-pyrrolidine-methanol (7.33 g, 7.16 mL, 72.6 mmol, 1.1 eq) and triethylamine (14.77 g, 20.21 mL, 145 mmol, 2.2 eq) in anhydrous CH2Cl2 (100 mL) at −40° C. (dry ice/CH3CN) under a N2 atmosphere. The reaction mixture was allowed to come to room temperature and stirred for 18 h. The mixture was washed with 1 M HCl (3×200 mL), H2O (2×200 mL), satd NaCl(aq) (200 mL), dried (MgSO4) and evaporated in vacuo to give a yellow foam. Trituration with 3% MeOH/EtOAc gave a white solid. Filtration and concentration of the filtrate gave a second crop of white solid. Total yield (18.13 g, 88.5%). mp 124.4-127.8° C.; [α]25D−109.00 (c=1.0, CHCl3); 1H NMR (CDCl3) δ 7.71 (s, 1H), 6.61 (s, 1H), 4.44-4.39 (m, 1H), 4.00 (s, 3H), 3.99 (s, 3H), 3.98-3.76 (m, 2H), 3.18 (m, 2H), 2.23-2.13 (m, 3H), 1.92-1.69 (m, 1H); 13C NMR (CDCl3) δ 164.4, 154.5, 149.2, 137.1, 127.8, 109.0, 107.2, 65.7, 61.3, 56.8, 56.5, 49.5, 28.3, 24.3; IR (neat) 3343, 2940, 1605, 1530, 1337, 1276, 1109, 1064, 992, 862, 788, 756 cm−1; HRMS m/z calcd for C14H18N2O7 310.1234 (M+H) found 311.1243.

1. customto come to room temperature
2. stirringstirred for 18 h
3. washThe mixture was washed with 1 M HCl (3×200 mL), H2O (2×200 mL), satd NaCl(aq) (200 mL)
4. dry with materialdried (MgSO4)
5. customevaporated in vacuo
6. customto give a yellow foam
7. filtrationFiltration and concentration of the filtrate
8. customgave a second crop of white solid
9. customTotal yield (18.13 g, 88.5%)