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To a solution of 44 (480 mg, 1.37 mmol) in CH2Cl2 (5 mL) was added TFA (5 mL). The reaction mixture was stirred for 2 h before being concentrated. The residue was subjected to chiral AD column chromatography (ethanol/MeOH/hexane/DEA=3:2:93:0.1) to give 47 as a single diastereomer. The absolute stereochemistry for the stereocenter in the side chain of 47 was not determined. A second stereoisomer was formed, but could not be isolated in pure form. 1H NMR (400 MHz, CDCl3)δ 7.32 (d, J=8.0 Hz, 1 H), 7.25 (d, J=2.4 Hz, 1 H), 7.19 (d, J=7.2 Hz, 1 H), 7.15-7.07 (m, 2 H), 6.94 (dd, J=2.4, 8.4 Hz, 1H), 6.82 (d, J=7.2 Hz, 1 H), 6.47 (s, 1 H), 4.01 (t, J=8.4 Hz, 1 H), 3.64(q, J=6.4 Hz, 1 H), 2.71 (dd, J=7.6, 16.8 Hz, 1 H), 2.48 (dd, J=8.0, 16.8 Hz, 1 H), 2.09 (broad, 2 H), 1.16 (d, J=8.0 Hz, 3 H); 13C NMR (100 MHz, CDCl3)δ 144.95, 143.12, 136.21, 134.01, 132.87, 130.42, 130.21, 128.02, 127.60, 127.62, 127.44, 126.78, 121.12, 52.47, 43.21, 32.58, 20.98; ESI MS m/z 318.0.

1. concentrationbefore being concentrated