Triethylamine → 3-(4-Phenyl-3,6-dihydropyridin-1(2H)-yl)propanoic acid

The 4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (1.5 g, 7.8 mmol) suspended in 16 mL of CH2Cl2. To this suspension was added triethylamine (2.1 mL, 15.3 mmol) followed by methyl 3-bromopropionate (1.0 mL, 9.2 mmol). The reaction was stirred at room temperature for 4 h and at reflux for 2 h. The reaction mixture was washed with water, 1N HCl (2×20 mL), 1N NaOH (2×20 mL) and Brine (1×20 mL). The organic layer was separated, dried over Na2SO4, filtered; and solvent was removed under reduced pressure. To the crude product was added 2N NaOH (15 mL). The mixture was stirred at reflux for 1 h. The reaction mixture was washed with CH2Cl2 (3×20 mL) and neutralized with concentrated HCl. The aqueous solution was concentrated to dryness under reduced pressure, to give a solid residue. Sodium chloride in the residue was removed in the following way (three repeats): dissolving the residue in a minimum amount of water, treating the aqueous solution with acetone, removing the resultant solid material by filtration, and concentrate the filtrate to dryness under reduced pressure. This allowed the isolation of compound Q (159.4 mg).