Reaction Steps
To a suspension of Compound 224 (1.10 g, 3.60 mmol) in dry CH2Cl2 (10 mL) under ice-cooling was added successively 2,6-lutidine (0.59 mL, 5.07 mmol) and tert-butyldimethylsilyl trifluoromethanesulfonate (0.99 mL, 4.31 mmol), the resultant homogeneous solution was then stirred at 25° C. for 30 minutes. The reaction mixture was diluted with CH2Cl2 (20 mL), washed with brine, dried over anhydrous Na2SO4, and evaporated in vacuo. The residue was purified by flash column chromatography (silica gel, ethyl ether-petroleum ether-benzene=1:2:2) to give Compound 225 (1.475 g, 98 percent): white solid; mp 123°-125° C.; Rf =0.50 (silica, 33 percent ethyl ether in benzene); IR (CHCl3) νmax 2952, 2933, 1621, 1506, 1336, 1295, 1256, 1240, 1174, 1151, 1090, 1025, 838 cm-1 ; 1H NMR (300 MHz, CDCl3) δ8.61 (s, 1 H, H6), 7.98 (d, J=9.2 Hz, 1 H, 1), 7.55-7.48 (m, 3 H, H4 and aromatic), 7.46-7.34 (m, 3 H, aromatic), 7.27 (dd, J=9.2, 2.7 Hz, 1 H, H2), 5.42 (t, J=2.6 Hz, 1 H, H10), 5.20 (s, 2 H, benzylic), 3.04-2.93 (m, 1 H, H7), 2.87-2.72 (m, 1 H, H7), 2.26-2.05 (m, 2 H, H8 or H9), 1.92-1.76 (m, 2 H, H8 or H9), 0.84 (s, 9 H, SiC(CH3)3), 0.22 (s, 6 H, Si(CH3)2); MS (FAB+) m/e (rel intensity) 420 (M+H, 100), 362 (23), 330 (3), 288 (9); HRMS for C26H34NO2Si (M+H), calcd 420.2359, found 420.2360.
