Ethyl 3-(1-pyrenyl)propanoate (1 equiv, prepared)
KOH (2 equiv, Fischer Scientific)
Ethanol
pH2 buffer solution (prepared)

Under a dinitrogen atmosphere, ethyl 3-(1-pyrenyl)propanoate (0.5 g, 1.6 mmol) was dissolved in warm ethanol (10 ml), then water (1 ml) and solid potassium hydroxide (0.18 g, 3.2 mmol) was added and the solution left stirring overnight. The reaction mixture was cooled and solvent removed under vacuo. Buffer solution (pH 2, 10 ml) was added and the mixture was extracted with ethyl acetate (10 ml x 3). The combined organics were dried over Na₂SO₄ and solvent was removed in vacuo to yield orange crystalline solid (0.45 g, 99%)

The reaction most probably takes less time (a couple of hours or so) however I just left it overnight to be sure.

δ_H(400MHz, CDCl₃) ppm: 2.94 (2H, t, J 8, CH₂), 3.72 (2H, t, J 8, CH₂), 7.92 (1H, d, J 8, aryl), 7.99 - 8.21 (7H, m, aryl), 8.28 (1H, d, J 9, aryl).

Ta-Hsien Chuang, Shiow-Ju Lee, Cheng-Wei Yang and Pei-Lin Wu, Expedient synthesis and structure–activity relationships of phenanthroindolizidine and phenanthroquinolizidine alkaloids, Org. Biomol. Chem., 2006, 4, 860–867