Hydrochloric Acid → HCID 69138262, compound

Participants

Reaction Conditions

Reaction Steps

16.5 mL of an n-butyllithium solution (2.5M in hexane) were added, under argon and at −40° C., to a solution of 5 g (20.66 mmol) of (S)-2-(4,4-dimethyl-2,5-dioxoimidazolidin-1-yl)-4-methylpentanoic acid (prepared in analogy with examples 1c) and 1d) using L-leucine in place of (S)-2-amino-3-cyclopropylpropionic acid) in 125 mL of absolute THF. The reaction mixture was allowed to warm to 0° C. and a solution of 6.28 g (20.66 mmol) of the compound of example 1b) in 40 mL of N-methyl-2-pyrrolidone and 20 mL of 1,3-dimethyl-2-imidazolidone was added. The reaction mixture was stirred at 0° C. for 1 h. 30 mL of 1N hydrochloric acid were then added and the THF was removed in vacuo. The residue was poured onto 300 mL of water. The precipitate was filtered off with suction, washed with water and taken up in dichloromethane. The solution was then added dropwise to 600 mL of methyl tert-butyl ether. The precipitate was filtered off and the organic phase was dried over magnesium sulfate. The desiccant was filtered off and the solvent was removed in vacuo. The residue was purified by means of preparative HPLC. 2.84 g (27%) of the title compound were obtained after concentrating the product fractions and subsequent freeze-drying.

Provenance & Evidence