After 2 h, the volatiles were removed in vacuo, diluted with 1:1 ethanol/1,4-dioxane, concentrated, and high-vacuum-dried to give N1-((1S)-3-chloro-2-oxo-1-{[(3S)-2-oxopyrrolidin-3-yl]methyl}propyl)-l-leucinamide hydrochloride as an off-white solid.