methyl 5-chloro-1H-pyrrole-2-carboxylate

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

Procedure: A mixture of sodium hydride (60%, 1.01 g, 25 mmol) and methyl 5-chloro-1H-pyrrole-2-carboxylate (J. Chem. Soc. 1965, 459–470, 2.96 g, 19.6 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, 3.90 g, 19.6 mmol) and the reaction mixture was stirred at 0° C. to rt overnight. The reaction mixture was diluted with saturated NaHCO3 solution and the product was extracted with EtOAc (3×100 mL). The EtOAc solution was washed with saturated NaHCO3 solution (4×60 mL), 10% LiCl solution (80 mL), brine (80 mL), dried over MgSO4 and concentrated in vacuo to give the crude product as a brown oil. The crude product was treated with 4 N HCl in dioxane in Et2O. The precipitated solid was collected, washed with Et2O and dried in vacuo to obtain the title compound (1.91 g, 50%): 1H NMR (DMSO-d6) δ 6.76 (d, 1H, J=4.4 Hz), 6.11 (d, 1H, J=4.4 Hz), 4.23 (q, 2H, J=6.02 Hz), 1.28 (t, 3H, J=6.02 Hz); 13C NMR (DMSO-d6) δ 159.9, 122.9, 120.3, 114.0, 104.6, 59.8, 14.3. the reaction mixture was stirred at 0° C. to rt overnight the product was extracted with EtOAc (3×100 mL) The EtOAc solution was washed with saturated NaHCO3 solution (4×60 mL), 10% LiCl solution (80 mL), brine (80 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 in vacuo