Hydrogen Bromide → 1,2,3,6-Tetrahydropyridine-4-carboxylic acid hydrobromide

Participants

Reaction Steps

To 104.4 g of ethyl 1-ethoxycarbonyl-1,2,3,6-tetrahydropyridine-4-carboxylate, 1500 g of 47% hydrobromic acid was added, and the mixture was heated under reflux for 100 hours. The reaction mixture was concentrated under reduced pressure to yield crude 1,2,3,6-tetrahydropyridine-4-carboxylic acid hydrobromide. The obtained crude 1,2,3,6-tetrahydropyridine-4-carboxylic acid hydrobromide was dissolved in a mixed solution of 0.48 l of dioxane and 0.48 l of a 2M aqueous solution of sodium hydroxide, and 105.2 g of tert-butyl bicarbonate were added thereto. The reaction mixture was stirred overnight at room temperature. The reaction mixture was concentrated under reduced pressure, and 1.4 l of a 1M aqueous solution of potassium hydrogensulfate was poured thereinto. The precipitated crystals of 1-tert-butoxycarbonyl-1,2,3,6-tetrahydropyridine-4-carboxylic acid was obtained in an amount of 100.5 g by filtration.

Provenance & Evidence