Sodium Hydroxide → 5-tert-butyl-3-nitro-1H-pyrrole-2-carboxylic acid

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Reaction Steps

Methyl 5-tert-butyl-3-nitropyrrole-2-carboxylate was prepared as described in Method N-1 Step 3. To a solution of methyl 5-tert-butyl-3-nitropyrrole-2-carboxylate (10.38 g, 45.9 mmol) in a THF—MeO—H2O mixture(1.0:1.0:0.5, 250 mL) at room temp. was added a 1N NaOH solution (92 mL, 92 mmol) via pippette. The color of the reaction mixture turned from green to red. The mixture was warmed to the reflux temperature, maintained for 3 hr, cooled to room temp. and concentrated in vacuo. The residue was made acidic using a 10% citric acid solution and was extracted with EtOAc (2×50 mL). The organic layer was washed with a saturated NaCl solution, dried (MgSO4), and concentrated in vacuo. The residue was triturated with hexanes to give 5-tert-butyl-3-nitropyrrole-2-carboxylic acid (9.70 g, 99%) as a green powder: 1H NMR (DMSO-d6) δ1.24 (s, 9H), 6.41 (d, J=2.9 Hz, 1H), 12.19 (br s, 1H), 13.50 (br s, 1H).

Provenance & Evidence