Synthesis
To a reaction flask equipped with a thermometer and a 1000 mL mechanical stirrer, 41 g (0.2 mol) of the second intermediate, 2-methyl-3,5-dicarbonyl-5-anilino-butane, and 250 mL of n-heptane were added under nitrogen protection. Heating was refluxed to remove the water generated and the reaction lasted for about 6 hours. After the reaction system was cooled to room temperature, catalyst glycine 4 g and glacial acetic acid 6 g were added sequentially, followed by benzaldehyde 24 g (0.22 mol). The reaction mixture was heated to reflux temperature and the reaction was continued for about 8 hours, during which the reaction progress was monitored by TLC. After completion of the reaction, it was cooled to room temperature and the reaction mixture was washed with 50 mL of saturated sodium chloride solution. After addition of 100 mL of n-heptane, the organic phase was separated and dried over anhydrous sodium sulfate. The filtrate was concentrated under reduced pressure to give 46 g of the target product 4-methyl-3-oxo-N-phenyl-2-(benzylidene)pentanamide.
References
[1] Organic and Biomolecular Chemistry, 2016, vol. 14, # 7, p. 2291 - 2296
[2] Tetrahedron Letters, 1992, vol. 33, # 17, p. 2283 - 2284
[3] RSC Advances, 2014, vol. 4, # 63, p. 33175 - 33183
[4] Journal of Labelled Compounds and Radiopharmaceuticals, 2000, vol. 43, # 3, p. 261 - 270
[5] Journal of the Indian Chemical Society, 2010, vol. 87, # 4, p. 495 - 499
