To the solution of 1 (naproxene, 691 mg, 3 mmol) in 20 mL of dimethylformamide, hydroxybenzotriazole (446 mg, 3.3 mmol) and DCC (619 mg, 3.3 mmol) were added with stirring at 0° C. for 1 h. To the reaction mixture 4-hydroxyphenylisothiocyanate (2; 500 mg, 3.3 mmol) was added and stirred for 1 h at 0° C. and 2 h at room temperature. After filtration, the filtrate was evaporated under reduced pressure to remove the solvent. The oily residue thus obtained was dissolved in ethyl acetate and the precipitate was removed. The solvent was evaporated and the crude product was loaded on a silica gel open column and eluted with dichloromethane, from which 4-(isothiocyano)-phenyl 2-(2-methoxynaphthalen-6-yl)propanoate (3) was obtained (230 mg, 21% yield).
