methyl 4-chloro-1H-pyrrole-2-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of sodium hydride (60%, 1.51 g, 38 mmol) and methyl 4-chloro-1H-pyrrole-2-carboxylate (Tetrahedron Letters, 1979, 27, 2505–2508; 4.80 g, 30 mmol) in DMF (40 mL) at 0° C. was stirred for 20 min, then was added 2, 4-dinitrophenolamine (Tetrahedron Lett. 1968, 16, 1909–1910 and J. Heterocyclic Chem. 1967, 413, 7.24 g, 36 mmol), and the reaction mixture was stirred at rt overnight. Water (100 mL) was added to the mixture, and the product was extracted with EtOAc (3×120 mL), the EtOAc solution was washed with 10% LiCl solution (2×120 mL), brine (120 mL), dried over MgSO4 and concentrated in vacuo to give the crude product as a brown oil. This crude product was treated with 4 N HCl in dioxane (8 mL) in Et2O (60 mL), the precipitated solid was collected, washed with Et2O and dried to give the title compound (5.40 g, 85%): 1H NMR (DMSO-d6) δ 7.17 (d, 1H, J=2.2 Hz), 6.68 (d, 1H, J=2.2 Hz), 3.74 (s, 3H). the reaction mixture was stirred at rt overnight the product was extracted with EtOAc (3×120 mL) the EtOAc solution was washed with 10% LiCl solution (2×120 mL), brine (120 mL) dried over MgSO4 concentrated in vacuo to give the crude product as a brown oil the precipitated solid was collected washed with Et2O dried