Reaction Steps
To a solution of aldol adduct 11 (0.150 g, 0.344 mmol, 1.0 equiv) in CH2Cl2 (10 mL) at −78° C. was added in a single portion a solution of TFA (0.027 mL, 0.344 mmol, 1.0 equiv) in CH2Cl2 (0.2 mL). The resultant dark purple reaction mixture was then warmed slowly to −20° C. over the course of 30 min and stirred for 5 h at −20° C. Upon completion, the reaction mixture was quenched sequentially with solid K2CO3 (0.475 g, 3.44 mmol, 10 equiv) and MeOH (10 mL), warmed to 25° C., and stirred for 15 min at 25° C. The reaction contents were then poured into water (15 mL) and extracted with EtOAc (3×40 mL). The combined organic layers were washed with water (15 mL) and brine (15 mL), dried (MgSO4), and concentrated. The resultant brown oil was purified by flash column chromatography (silica gel, EtOAc/hexanes, 2:1) to give alcohol 15 (0.113 g, 75% yield) as an amorphous white solid. 15: Rf=0.41 (silica gel, EtOAc/hexanes, 1:1); IR (film) νmax 2935, 1597, 1512, 1463, 1304, 1248, 1203, 1151, 1060, 829; 1H NMR (300 MHz, CDCl3) δ 7.09 (d, J=8.7 Hz, 2H), 6.83 (d, J=8.7 Hz, 2H), 6.65 (d, J=2.1 Hz, 1H), 6.42 (d, J=2.1 Hz, 1H), 6.27 (t, J=2.3 Hz, 1H), 6.17 (d, J=2.4 Hz, 2H), 5.13 (app t, J=5.7 Hz, 1H), 4.19 (d, J=6.9 Hz, 1H), 3.86 (s, 3H), 3.79 (s, 3H), 3.68 (s, 3H), 3.59 (s, 3H), 3.18 (d, J=6.6 Hz, 1H); 13C NMR (75 MHz, CDCl3) δ 161.7, 160.4, 158.5, 157.1, 146.9, 146.3, 134.0, 128.7, 122.9, 113.9, 105.5, 99.7, 99.4, 99.3, 98.0, 82.5, 66.1, 55.6, 55.3, 55.2, 54.7; HRMS (MALDI-FTMS) calculated for C26H21O6+ [M+] 436.1886. found 436.1870.
