反应详情

To a solution of 5-methyl-4-nitro-2-thiophene carboxylic acid (4.6 g, 24.6 mmol) in DMF (14.5 mmol) was added N,N-dimethylformamide dimethyl acetal (3.8 mL, 28.5 mmol) and pyrrolidine (2 drops). The mixture was refluxed for 3 h, concentrated in vacuo and the residue taken up in EtOAc (0.2 L). The organic phase was washed with water, saturated aq NaCl, dried over Na2SO4, filtered and concentrated in vacuo. The crude product was chromatographed over silica gel (0 to 40% EtOAc/heptane over 60 min) to give methyl 5-(2-dimethylaminovinyl)-4-nitrothiophene-2-carboxylate as a dark red solid (1.0 g, 16%). 1H NMR (400 MHz, CDCl3) δ (ppm) 8.10 (s, 1H) 7.31 (d, J=13.1 Hz, 1H) 6.56 (d, J=13.1 Hz, 1H) 3.87 (s, 3H) 3.07 (s, 6H). LCMS m/e 279 (M+Na).

1. temperatureThe mixture was refluxed for 3 h
2. concentrationconcentrated in vacuo
3. washThe organic phase was washed with water, saturated aq NaCl
4. dry with materialdried over Na2SO4
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customThe crude product was chromatographed over silica gel (0 to 40% EtOAc/heptane over 60 min)