Galactaric acid (314.0 mg, 1.49 mmol) was dissolved in 2-propanol (10 mL) and water (˜1 mL), assisted by heating and sonicating over a period of 10 min. A solution of (2R)-(4E)-N-methyl-5-(5-isopropoxy-3-pyridyl)-4-penten-2-amine (700.3 mg, 2.99 mmol) in 2-propanol (10 mL) was then added, followed by additional sonicating and heating at 60° C. for 10 min. The hot solution was filtered to remove some insoluble material. The solvent was removed on a rotary evaporator; the resulting light-brown syrup was dissolved in dry 2-propanol (5 mL) and cooled at 4° C. The resulting precipitate was filtered and dried under high vacuum to yield 657 mg (64.8%) of an off-white, crystalline powder, mp 150-153° C.
