Reaction Steps
To a solution of compound 52 (75 mg, 0.14 mmol) and MeI (86 μL, 1.4 mmol) in DMSO (2.0 mL) was added powdered KOH (23 mg, 0.42 mmol) and the resulting mixture was stirred for 5 min (until no starting material was present by TLC, developed in 1:3 EA/hexanes) at room temperature. 5 mL of H2O was added, and extracted with diethyl ether (3×5 mL). The organic layers were combined washed with brine, dried over anhydrous Na2SO4 and concentrated. Flash chromatography (ethyl acetate/hexane, 1:10) afforded 72 mg (yield 94%) of compound 53 as a colorless oil which slowly solidified when left standing. m.p.=94.0° C.-96.0° C.; [α]20D=−39.7 (c=0.65, CHCl3); 1H NMR (CDCl3, 300 MHz) δ 7.86-7.89 (m, 2H), 7.51-7.61 (m, 3H), 7.35 (d, J=7.8 Hz, 1H), 3.98 (s, 1H), 3.83 (d, J=3.9 Hz, 1H), 3.57 (d, J=9.3 Hz, 1H), 3.35 (s, 3H), 2.77 (m, 1H), 2.54 (m, 1H), 1.23 (d, J=7.2 Hz, 3H), 1.01 (d, J=7.2 Hz, 3H), 0.91 (s, 9H), 0.84 (s, 9H), 0.09 (s, 3H), 0.07 (s, 3H), −0.14 (s, 3H), −0.31 (s, 3H). 13C NMR (CDCl3, 75 MHz) δ 149.4, 140.3, 139.9, 133.4, 129.4, 128.3, 79.8, 78.7, 73.7, 59.4, 40.2, 36.6, 26.1, 28.3, 18.2, 17.7, 16.9, −4.1, −4.5, −4.6, −4.7; LRMS (CI) m/z 555 [M+H]+; HRMS (CI) calculated for C28H50O5SSi2, 555.2996; found, 555.2998.
