Reaction Steps
To a solution of Compound 211 (2.80 g, 4.95 mmol) in THF-EtOH-H2O (1:1:1, 300 mL) was added silver nitrate (3.36 g, 19.8 mmol) followed by stirring at 25° C. for one hour. Potassium cynide (2.26 g, 34.65 mmol) was added to the reaction mixture followed by stirring at 25° C. for another 10 minutes. The reaction mixture was diluted with CH2Cl2 (300 mL), washed with brine, dried over anhydrous Na2SO4, and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel, 50 percent ethyl ether in petroleum ether) to furnish Compound 212 (2.20 g, 90 percent): Rf =0.43 (silica, 50 percent ethyl ether in petroleum ether); IR (CHCl3) νmax 3302, 2959, 1740 (shoulder), 1725 (shoulder), 1719, 1680, 1606, 1494, 1381, 1307, 1177, 1123 cm-1 ; 1H NMR (300 MHz, CDCl3 ) δ 8.25 (d, J=8.8 Hz, 1 H, H1), 7.50-7.17 (m, 6 H, H4and aromatic), 6.95 (dd, J=8.8, 1.1 Hz, 1 H, H2), 6.06 (s, 1 H, H6), 5.79 (s, 2 H, olefinic), 3.32 (d, J=1.0 Hz, 1 H, acetylenic), 2.86 (dt, J=18.9, 4.5 Hz, 1 H, H9), 2.76-2.51 (m, 3 H, H7 and H9), 2.23-2.16 (m, 2 H, H8), 1.33 (s, 9 H, COC(CH3)3); MS (FAB+) m/e (rel intensity) 626 (M+Cs, 16), 418 (13); HRMS for C31H27NO5Cs (M+Cs), calcd 626.0944, found 626.0975.
