Dimethyl Sulfate → Ethyl 1-methyl-4-nitro-3-methoxypyrrole-2-carboxylate

Participants

Reaction Steps

A mixture of ethyl 1-methyl-4-nitro-3-hydroxypyrrole-2-carboxylate (0.071 g, 0.3315 mmol), dimethyl sulfate (0.055 g, 0.436 mmol) and anhydrous potassium carbonate (0.5 g, 3.90 mmol) in dry acetone (20 mL) was refluxed under a nitrogen atmosphere for 22 h. Potassium carbonate was removed by filtration and the filtrate was evaporated under reduced pressure to afford an orange crystalline solid. Excess dimethyl sulfate was destroyed by treating the residue with aqueous ammonia (1 mL). Water (2 mL) was added and the residue was extracted with ether (30 mL). The combined ether extracts were washed with aqueous sodium hydroxide solution and water. Removal of ether under reduced pressure afforded a cream residue. The residue was dissolved in CH2Cl2 (25 mL), dried with anhydrous Na2SO41 filtered and evaporated under reduced pressure to yield a cream microcrystalline solid (0.067 g, 89%). Recrystallization from acetone/hexane afforded colorless needles, mp 145-147° C.; 1H NMR (300 MHZ, CDCl3) d 1.40 (t, J=7.2 Hz, 3H, CH3—CH2—), 3.90 (s, 3H, CH3—N—), 3.95 (s, 3H, CH3O—), 4.36 (q, J=7.0 Hz, 2H, CH3—CH2—), 7.47 (s, 1H, H-5); 13C NMR (100 MHZ, CDCl3) d 14.22, 38.92, 60.67, 63.02, 114.73, 125.76, 127.79, 146.18, 160.09; MS (EI, 70 eV) m/z (relative intensity) 229 (M+1, 3), 228 (M+, 30), 211 (12), 183 (12), 167 (20), 153 (25), 152 (100), 141 (7), 109 (12), 84 (8), 67 (6), 53 (31), 42 (17), Calcd for C9H12N2O5: 228.20. HRMS (M+H): Calcd for C9H13N2O5 [M+H+]: 229.0824, Found 229.0834. Anal. Calcd for C9H12N2O5: C, 47.37; H, 5.29; N, 12.27. Found. C, 47.44; H, 5.36; N, 12.28. TLC (ethyl acetate/Hexane, 1:3) Rf 0.23.

Provenance & Evidence