反应详情

p-Hydroxybenzoic acid (2.62 g, 19.0 mmol) was added in portions to a stirred solution (2S)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridinyl)-4-penten-2-amine (4.79 g of 93% pure, 19.0 mmol) in isopropyl acetate (50 mL). During the addition, crystallization of salt was evident. After complete addition of the p-hydroxybenzoic acid, the suspension was heated near its boiling point as isopropanol was slowly added. After 15 mL of isopropanol had been added, complete dissolution was obtained. Cooling of the solution to ambient temperature (overnight) resulted in deposition of a crystalline mass, which was collected by suction filtration and air dried (4.03 g). A second crop (0.82 g) was isolated from the concentrated filtrate, by addition of acetone. The two crops of crystals were combined and recrystallized from acetone (50 mL). The solid was collected by suction filtration and dried in the vacuum oven (50° C.) for 18 h. This left 4.24 g (60.0%) of white crystals (98+% pure by both GCMS and LCMS; m.p. 99-101° C.).

1. additionDuring the addition, crystallization of salt
2. temperaturethe suspension was heated near its
3. additionwas slowly added
4. dissolutioncomplete dissolution
5. customwas obtained
6. customresulted in deposition of a crystalline mass, which
7. filtrationwas collected by suction filtration and air
8. customdried (4.03 g)
9. customA second crop (0.82 g) was isolated from the concentrated filtrate, by addition of acetone
10. customrecrystallized from acetone (50 mL)
11. filtrationThe solid was collected by suction filtration
12. customdried in the vacuum oven (50° C.) for 18 h