Reaction Steps
To a solution of 33 (3.0 g, 9.3 mmol) in ethyl ether (100 mL) at 0° C. was added lithium aluminum hydride (1.0 M in ethyl ether, 47 mmol). After stirring for 15 min at 0° C. under argon, the reaction mixture was diluted with ethyl ether (300 mL) and quenched with saturated aqueous Na2SO4 until evolution of hydrogen had ceased. The mixture was dried with solid Na2SO4 and filtered, and the residue was extracted with ether (50 mL). The organic extracts were combined and concentrated in vacuo. Flash chromatography over silica gel (1/9 EtOAc:hexane) gave pure 34 as a colorless oil (2.1 g, 69%): Rf=0.60 (1/9 EtOAc:hexane); 1H NMR (300 MHz, CDCl3) δ 7.57 (m, 4H), 7.37 (m, 6H), 5.87 (m, 1H), 4.97 (dd. J=17.11.7 Hz, 1H), 4.88 (dd, J=102, 1.7 Hz, 1H), 4.08 (d, J=12.1 Hz, 1H), 2.12 (m, 2H), 1.85 (m, 1H), 1.58 (m, 1H), 1.26 (m, 4H), 0.88 (d, J=6.2 Hz, 6H); 13C NMR (75 MHz, CDCl3) δ 141.4, 135.7, 133.8, 129.8, 128.2, 113.3, 61.5, 42.4, 27.5, 24.2, 23.7, 20.7, 9.8; IR (neat) 3565 (m), 3452 (m, br), 3069 (m), 3050 (m), 2955 (s), 2910 (s), 2869 (m), 1965 (w), 1894 (w), 1832 (w), 1642 (m), 1469 (m), 1434 (s), 1369 (w), 1116 (s), 1001 m), 916 (m), 743 (s), 705 (s) cm−1; MS (FAB) m/e (rel. intensity) 323 (MH+-2, 5), 269 (21), 238 (11), 198 (57), 1.83 (100), 181 (10), 177 (23), 161 (14) 159 (56), 123 (15), 99 (12); HRMS (FAB) calcd for C21H27OSi: 323.1831 (MH+-2), found: 323.1824. Anal. Calcd for C21H28SiO: C, 77.72; H, 8.70. Found: C, 77.60; H, 8.67.
