A solution of 29, N2-(tert-butoxycarbonyl)-N1-((1S)-3-chloro-2-oxo-1-{[(3S)-2-oxopyrrolidin-3-yl]methyl}propyl)-l-leucinamide (244 mg, 0.59 mmol) in 1,4-dioxane (1.0 mL) was placed under an atmosphere of N2. This clear colorless solution was treated with a solution of 4 M hydrochloric acid in 1,4-dioxane with no observable change. The reaction gradually became opaque with the formation of a gummy precipitate. 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. 1H NMR (DMSO-d6) δ 9.18 (d, J = 8 Hz, 1H), 8.40 (bs, 3H), 7.69 (s, 1H), 4.68 (s, 2H), 4.49 (m, 1H), 3.81 (m, 1H), 3.15 (m, 2H), 2.37 (m, 1H), 2.17 (m, 1H), 1.92 (m, 1H), 1.67 (m, 3H), 1.55 (m, 2H), 0.92 (d, J = 4 Hz, 3H), 0.88 (d, J = 4 Hz, 3H); MS (ESI+) for C14H24ClN3O3m/z 318.1 (M + H)+.