Reaction Steps
A solution of 24.0 mg (0.076 mmol, 1.0 eq) of alcohol 16 in 5.0 mL of dry CH2Cl2 was stirred in a 5 mL round bottom flask at room temperature under argon. To this solution was added 36.6 μL of Et3SiH (0.229 mmol, 3.0 eq). The solution was then cooled to 0° C. in an ice water bath. After cooling, 28.0 μL (0.220 mmol, 2.9 eq) of BF3-Et2O was slowly added and the resulting solution was stirred until all the starting material was consumed by TLC (1:1 hexane:EtOAc, Rf=0.56). After alcohol 16 was completely consumed (˜15 minutes), 69.0 mg (0.456 mmol, 6.0 eq) of TBSCl and 31.0 mg (0.456 mmol, 6.0 eq) of imidazole were added at once and the ice water bath was removed. The solution was then stirred at room temperature until the reaction was complete by TLC (1:1 hexane:EtOAc, Rf=0.80). Upon completion (˜18 hours) the solution was diluted with CH2Cl2 and washed with a saturated aqueous NH4Cl solution. The aqueous layer was then extracted twice with CH2Cl2 and the combined organic fractions were dried over MgSO4 and concentrated. Silica gel chromatography (hexane/EtOAc) yielded 116 mg (69%) of 17 as a colorless solid, Rf 0.80 (1:1 hexane:EtOAc). Mp: 92.4-93.5° C. 1H-NMR (500 MHz, CDCl3): 8.31 (1H, m), 8.10 (1H, m), 7.47 (3H, m), 4.20 (2H, q, J=7.1 Hz), 3.29 (2H, t, J=7.6 Hz), 2.93 (3H, s), 2.78 (2H, t, J=7.7 Hz), 1.28 (3H, t, J=7.2 Hz), 1.15 (9H, s), 0.27 (6H, s). 13C-NMR (500 MHz, CDCl3): 172.93, 143.40, 143.25, 132.82, 130.16, 127.98, 125.74, 124.02, 123.87, 123.69, 122.69, 119.97, 118.53, 60.84, 34.56, 26.24, 21.79, 18.93, 14.45, 14.42, −3.86. IR (cm−1): 2960 (m), 2854 (w), 1740 (vs), 1630 (w), 1461 (m), 1389 (s), 1247 (m), 1117 (m), 985 (s), 828 (s), 752 (s). Anal. Calcd. for C24H32O4Si: C, 69.86; H, 7.82. Found: C, 70.18; H, 8.02.
