Triethylamine → {3-[(5-Formyl-2,4-dimethyl-1H-pyrrole-3-carbonyl)-amino]-propyl}-carbamic acid tert-butyl ester

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Reaction Steps

To a solution of 5-formyl-2,4-dimethyl-1H-pyrazol-3-carboxylic acid (0.300 g, 1.79 mmol), N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide (0.516 g, 2.69 mmol), 1-Hydroxybenzotriazole hydrate (0.364 g, 2.69 mmol), triethylamine (0.502 ml, 3.56 mmol) in dimethylformamide (3 ml) was added N-Boc-1,3-diaminopropane (0.375 ml, 2.15 mmol). The solution was stirred at room temperature for 15 hours. A mixture of brine (1.5 ml), water (1.5 ml) and saturated aqueous sodium bicarbonate (1.5 ml) was added and the pH of the solution adjusted to 12 by addition of 10N sodium hydroxide. The solution was extracted 3 times with a mixture of dichloromethane:Methanol (9:1). The organic layer was dried with anhydrous magnesium sulfate. The solvent was removed and the residue purified by flash chromatography (Hexane:Ethyl acetate (50 to 100%)) to yield the desired compound as a yellow solid (0.30 g, 52%). 1H NMR (400 MHz, DMSO-d6) δ 11.90 (s, 1H); 9.50 (s, 1H); 7.50 (m, 1H); 6.90 (m, 1H); 3.20 (q, 2H); 3.00 (q, 2H); 2.30 (s, 3H)); 2.20 (s, 3H)); 1.60 (m, 2H)); 1.40 (s, 9H). LCMS: method D, RT=2.103 min, [M+Na+=346], and [M−Boc+Na+=246].

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