Synthesis
The general procedure for the synthesis of 5,6-dihydro-2(1H)-pyridinone from the compound (CAS:1415686-28-0) was as follows: intermediate 1 (41.6 g, 0.33 mol) was dissolved in 416 ml of anhydrous toluene, and the second-generation Grubbs catalyst (0.7 g) was added under stirring. The reaction mixture was heated to 85?90 °C and the reaction was continuously stirred for 7 hours. The reaction progress was monitored by gas chromatography (GC) and after confirming the completion of the reaction, the reaction mixture was cooled to room temperature. Subsequently, 8.5 ml of ammonia was added and stirring was continued for 1 hour. The reaction mixture was washed with water (3 x 30 ml) and the organic phase was dried with anhydrous Na2SO4. After filtration to remove the desiccant, the filtrate was concentrated to dryness under reduced pressure. To the concentrate, 300 ml of isopropyl ether was added and refluxed for 20 min, then cooled to -5?0 °C and allowed to stand for 6 h. The solid was collected by filtration. The solid was collected by filtration and washed with appropriate amount of isopropyl ether to give 24 g of intermediate 2 (white powdery solid) in 75% yield.
References
[1] Patent: CN106432189, 2017, A. Location in patent: Paragraph 0011; 0020
[2] European Journal of Medicinal Chemistry, 2012, vol. 57, p. 344 - 361
[3] European Journal of Medicinal Chemistry, 2016, vol. 107, p. 233 - 244
[4] European Journal of Medicinal Chemistry, 2017, vol. 125, p. 453 - 463
[5] Chemistry of Heterocyclic Compounds, 2016, vol. 52, # 3, p. 183 - 191
