To tert-butyl 2-benzylpiperazine-1-carboxylate (0.052 g, 0.190 mmol), 2-(2-oxo-3,3-diphenylpyrrolidin-1-yl)acetic acid (Example 1C, 0.051 g, 0.173 mmol) and 2-(1H-benzo[d][1,2,3]triazol-1-yl)-1,1,3,3-tetramethylisouronium hexafluorophosphate(V) (0.069 g, 0.181 mmol) in dichloromethane (0.5 mL) was added diisopropylethylamine (0.045 mL, 0.259 mmol), and the reaction was stirred a room temperature. After stirring overnight, the reaction was concentrated, loaded onto a silica gel column (Analogix® SF15-12, Burlington, Wis.) and eluted with a gradient of 5% to 100% ethyl acetate/hexanes. To the resulting product was added HCl (2.0 Min diethyl ether, 3.57 μl, 0.117 mmol), and the reaction was stirred at room temperature overnight. The reaction was centrifuged, and the solvent was decanted away from the solid. Diethyl ether (1 mL) was added, and the suspension was sonicated to give a fine suspension. The reaction was centrifuged, the solvent was decanted and the resulting solid dried to give the title compound as the hydrochloride salt. 1H NMR (300 MHz, pyridine-d5) δ ppm 7.05-7.50 (m, 15H), 4.65-4.80 (m, 2H), 4.25-4.55 (m, 2H), 3.95-4.15 (m, 2H), 3.40-3.75 (m, 5H), 2.95-3.27 (m, 2H), 2.75-2.85 (m, 2H); MS (DCI+) m/z 454.2 (M+H)+.
