DIEA (0.014 mL, 0.073 mmol) was added to 8-hydroxy-3-carboxy-coumarin (0.015 g, 0.066 mmol) and HATU (0.030 g, 0.073 mmol) in 0.36 mL of DMF with constant stirring at room temperature until a clear solution resulted. Subsequently, 3-(1H-Indol-5-yl)-phenylamine (0.015 g, 0.066 mmol) was added and allowed to react overnight. DMF was removed under vacuum and the reaction was resuspended in DMSO. The crude product was purified on a Parallex Flex parallel preparative reverse phase HPLC instrument (Biotage) using a solvent gradient of 10-95% ACN/H2O with 0.05% TFA at a flow rate of 20 mL/min. UV absorbance was monitored at 254 nm and the fractions corresponding to the product peak were collected and the solvent removed under vacuum to give 0.017 g of product in 61% yield: LCMS (ESI) m/z 397 (MH+).
