Diisopropylethylamine (DIEA, 0.0115 mL, 0.067 mmol) was added to 8-hydroxy-3-carboxy-coumarin (0.012 g, 0.06 mmol) and O-(7-Azabenzotriazole-1-yl)-N,N,N,N′-tetramethyluronium hexafluorophosphate (HATU, 0.025 g, 0.067 mmol) in 0.5 mL of dimethylformamide (DMF) with constant stirring at room temperature until a clear solution resulted. Subsequently, 3-(6-methoxy-naphthalen-2-yl)-phenylamine (0.015 g, 0.06 mmol) was added and allowed to react overnight. DMF was removed under vacuum and the reaction was resuspended in dimethylsulfoxide (DMSO). The crude product was purified on a Parallex Flex parallel preparative reverse phase HPLC instrument (Biotage) using a solvent gradient of 10-95% acetonitrile (ACN)/H2O with 0.05% trifluoroacetic acid (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. Solvent was removed under vacuum and the resulting solid was left overnight in vacuo to give 0.010 g of product in 38% yield: LCMS (ESI) m/z 438 (MH+).
