Trimethylamine → N,N'-Dicyclohexylurea

Participants

Reaction Steps

To a solution of L-alanine methyl ester hydrochloride (5.97 g, 42.8 mmol) in CH2Cl2 (100 ml) was added Et3N (4.33 g, 42.8 mmol), and the mixture was stirred for 20 minutes at room temperature. A solution of Me3N.BH2COOH (5.00 g, 42.8 mmol) in CH2Cl2 (50 ml) was then added to the reaction mixture, followed by N,N'-dicyclohexylcarbodiimide (DCC) (9.27 g, 49.1 mmol) in CH2Cl2 (50 ml). After 72 hours, the N,N'-dicyclohexylurea (DCU) precipitate which formed was filtered off, and the solvent was removed under reduced pressure. The solid residue was then washed with diethyl ether (3×300 ml), and the combined washes were filtered prior to removal of the ether under reduced pressure. This procedure was repeated with water (3×300 ml) as solvent, following which, evaporation of the water from the combined washes was aided by passage of a dry air stream over the solution. Further purification of the resulting yellow oil was performed by flash chromatography using ethyl acetate/acetone (95:5) as the mobile phase. After the peptide-containing fractions were combined and the solvent removed in vacuo, the peptide oil was distilled under vacuum at 50° C. Final purification of the distilled oil was performed by flash chromatography on a column packed with petroleum ether and eluted with ethyl acetate/n-butyl alcohol (95:5). The peptide-containing fractions were combined, and the solvent was removed by the passage of a dry air stream over the solution to give the desired crystalline dipeptide. (Due to the hygroscopic nature of (1), a clear oil may result, which may be crystallized by storage under high-vacuum for several weeks.) Yield: 0.452 g (5.23%).

Provenance & Evidence