Diethyl Succinate → (3E)-3-(Ethoxycarbonyl)-4-(5-ethyl-2-furyl)but-3-enoic acid

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Reaction Steps

To a suspension of tBuOK (61.4 g, 0.54 mol) in tBuOH (180 mL) was added a suspension of 5-ethyl-2-furaldehyde (22.5 g, 0.18 mol) in succinic acid diethyl ester (142.1 g, 0.82 mol). The reaction mixture was refluxed for 1 h. Then the same amounts of tBuOK, tBuOH and succinic acid diethyl ester were added at the same temperature, and the reaction mixture was stirred at reflux for another 1 h. TLC (petroleum ether/EtOAc 2:1) indicated the complete consumption of the furaldehyde. The reaction mixture was allowed to cool to room temperature, acidified to a pH˜2 by 20% aqueous HCl (200 mL) and extracted with EtOAc (500 mL×3). The organic phase was washed with 10% aqueous Na2CO3 (500 mL×3). The combined aqueous layers was washed with ethyl ether (500 mL) and acidified to a pH˜2 with 20% aqueous HCl (100 mL). The aqueous phase was finally extracted with EtOAc (500 mL×4). The combined organic layers were dried over Na2SO4 and concentrated to give the crude acid (45.4 g, 100%), which was directly used to next step without further purification.

Provenance & Evidence