To a suspension of 58 (1.25 g, 3.0 mmol) in acetic acid (30 mL) was added ammonium formate (1.50 g, 24 mmol) and 10% Pd on carbon (1.30 g). After vigorous refluxing for 16 h, the mixture was filtered through Celite, which was subsequently washed with ethyl acetate (100 mL). The mixture was washed with water (2×75 mL), 1N NaHCO3 (50 mL), brine (75 mL) then dried (MgSO4), filtered and concentrated in vacuo. The crude product was dissolved in dichloromethane, adsorbed onto silica gel and purified by flash chromatography using hexanes:ethyl acetate (3:7) to yield a white solid (0.48 g, 38%) after concentration then trituration and filtration from hexanes-ethyl acetate (4:1). 1H NMR (400 MHz, DMSO-d6): δ 12.04 (br s, 1H), 7.58 (d, J=8.8 Hz, 2H), 7.43 (t, J=7.6 Hz, 1H), 7.39 (dt, J=8.0, 1.6 Hz, 1H), 7.27 (d, J=8.8 Hz, 2H), 7.22 (t, J=2.0 Hz, 1H), 7.01 (d, J=8.8 Hz, 2H), 7.00 (d, J=9.2 Hz, 2H), 4.91 (dd, J=8.8 and 4.4 Hz, 1H), 3.79 (s, 3H), 3.37 (dd, J=14.4 and 4.4 Hz, 1H), 3.13 (dd, J=14.4 and 8.8 Hz, 1H).
