1-(4-chlorobenzyl)-1H-indole-2-carboxylic acid (2.4 g, 8.40 mmol), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (2.4 g, 12.60 mmol), and 1-Hydroxybenzotriazole hydrate (1.9 g, 12.60 mmol) were dissolved in 20.0 mL of DCM. The resulting suspension was stirred for twenty minutes where it turned into a clear, yellow solution. N,N-Diisopropylethylamine (2.2 mL, 12.60 mmol) and ethyl piperidine-4-carboxylate (1.94 mL, 12.60 mmol) were added to the reaction. The reaction was stirred overnight. Water was added to the reaction followed by ethyl acetate. The layers were separated and the organic layer was washed sequentially with 1N HCl, saturated sodium bicarbonate, and saturated sodium chloride. The organic layer was dried over magnesium sulfate, filtered and concentrated. The resulting crude mixture was triturated with diethyl ether to obtain pure product as a white solid. Yield: 2.79 g, (White solid)
