Ethanol → Diethyl 1-benzyl-3,4-dihydroxy-1H-pyrrole-2,5-dicarboxylate

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Reaction Steps

Into a 20L three-necked flask, 2.7L of ethanol was put, and 139.2 g (6.05 moles) of small cuts of metallic sodium were gradually added thereto with stirring at room temperature. After the addition was completed, the mixture was stirred under reflux until the metallic sodium became dissolved completely. The mixture formed was cooled to room temperature, and 770.7 g (2.760 moles) of the diethyl N-benzyliminodiacetate and 405.8 g (2.775 moles) of diethyl oxalate were added thereto, which were then stirred under reflux for 8 hours. After the reaction was completed, the reaction product was left to cool, and its pH was adjusted to 5.5 by adding 4.5L of acetic acid. The precipitate formed was collected by filtration and washed with water. This precipitate was washed with acetone to obtain 532.8 g of diethyl N-benzyl-3,4-dihydroxypyrrole-2,5-dicarboxylate (yield: 57.9%), having a melting point of 143.5 to 145.0° C.

Provenance & Evidence