Reaction Steps
To ketone 6b (240 mg, 0.67 mmol) dissolved in 20 mL of methylene chloride stirring at 0° C. was added 2.7 mL of BBr3 (1.0 M in methylene chloride, 2.69 mmol). After stirring for one hour at 0° C., 6b was still present, and the reaction was allowed to reach room temperature over the next two hours. The reaction was then quenched with methanol, and water was added to the mixture. The aqueous phase was then extracted 3 times with methylene chloride (3×50 mL). The combined organic extracts were dried with MgSO4 and concentrated. The crude mixture was purified by flash chromatography to give 7b (190 mg, 0.578 mmol, 86%) as a white crystalline solid. 1H NMR (400 MHz, (CD3)2CO) δ 7.76 (s, 1H), 7.73 (s, 1H), 6.24 (t, J=0.96 Hz, 1H), 6.13 (d, J=1.6 Hz, 1H)), 2.66-2.61 (m, 1H), 2.59-2.52 (m, 2H), 2.49-2.46 (m, 1H), 2.44-2.37 (m, 1H), 1.86-1.82 (m, 1H), 1.81-1.77 (m, 1H), 1.76-1.71 (m, 1H), 1.67-1.55 (m, 4H), 1.15 (s, 3H), 1.13 (s, 3H), 1.07 (s, 3H), 1.09 (s, 3H); 13C NMR (100 MHz, (CD3)2CO) δ 216.9, 158.5, 154.8, 146.7, 131.9, 105.8, 102.8, 65.4, 57.2, 48.9, 47.3, 40.5, 39.6, 38.0, 35.4, 30.9, 27.9, 22.2, 22.1, 21.3, 16.9. ESIMS [M+Na]+ calcd for C21H28O3Na 351.1936, found 351.1929. [α]24D=+24.07°.
