Reaction Steps
To a suspension of Compound 141a (1.00 g, 3.03 mmol) in dry THF (20 mL) cooled in an ice-water bath was added NaH (60 percent, 128 mg, 3.19 mmol) followed by stirring for 10 minutes. To the resultant solution was added 2-nitrobenzyl bromide (0.689 g, 3.19 mmol) and tetra-n-butylammonium iodide (0.11 g, 0.3 mmol), and the mixture was then stirred at 25° C. for one hour. Water was added to the reaction mixture followed by extraction with ethyl acetate (50 mL), washing with brine, dry over anhydrous Na2SO4, and concentration in vacuo to give a crude product. Flash column chromatography of the crude product (silica gel, 20 percent ethyl ether in benzene) afforded Compound 143a (1.27 g, 90 percent): pale-yellow solid; mp 150°-152° C.; Rf =0.33 (silica, 20 percent ethyl ether in benzene); IR (CHCl3) νmax 2953, 2933, 1623, 1528, 1343, 1090, 1027, 838 cm-1 ; 1H NMR (300 MHz, CDCl3) δ 8.60 (s, 1 H, H6), 8.21 (dd, J=8.0, 0.9 Hz, 1 H, aromatic), 8.01 (d, J=9.2 Hz, 1 H, H1), 7.92 (d, J=7.8 Hz, 1 H, aromatic), 7.68 (dt, J=7.8, 0.9 Hz, 1 H, aromatic), 7.50 (t, J=8.0 Hz, 1 H, aromatic), 7.44 (d, J=2.6 Hz, 1 H, H4), 7.32 (dd, J=9.2, 2.6 Hz, 1 H, H2), 5.66 (s, 2 H, benzylic), 5.42 (t, J=3.1 Hz, 1 H, H10), 2.97 (br dd, J=14.0, 4.0 Hz, 1 H, H7), 2.86-2.72 (m, 1 H, H7), 2.25-2.15 (m, 2 H, H8 or H9), 1.90-1.80 (m, 2 H, H8 or H9), 0.85 (s, 9 H, SiC(CH3)3), 0.22 (s, 6 H, Si(CH3)2); MS (FAB+) m/e (rel intensity) 465 (M+Cs, 100), 407 (19), 330 (26), 198 (17), 136 (18); HRMS for C26H32N2O4SiCs (M+Cs), calcd 465.2210, found 465.2210. Anal. Calcd for C26H32N2O4Si: C, 67.21; H, 6.94; N, 6.03. Found: C, 67.31; H, 6.91; N, 5.96.
