Acetonitrile → ethyl 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylate

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Reaction Conditions

Reaction Steps

3,5-Dimethyl-1H-pyrrole-2-carboxylic acid ethyl ester (204 g), 177 g of potassium carbonate and 1428 mL of acetonitrile were stirred and cooled to 4° C. in an ice bath. N-Bromosuccinimide (228 g) was added in portions with vigorous stirring keeping the temperature below 17° C. The mixture was warmed to 20° C. and 2856 mL of water was slowly added. The mixture was stirred for 30 minutes. The precipitate was collected by vacuum filtration and washed three times with 400 mL of ethanol:water 1:2 each time. The solids were dried under vacuum at 60° C. to give 228 g (76% yield) of 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid ethyl ester as an off-white solid. 1H-NMR (dimethylsulfoxide-d6) δ 1.26 (t, 3H, CH3), 2.14, 2.17 (2×s, 2×3H, 2×CH3), 4.20 (d, 2H, CH2O), 11.75 (br s, 1H, NH). MS m/z 246, 248 [M+1].

Provenance & Evidence