S=C1[N:6]([C:7]([O:9][CH2:10][C:11]2[CH:16]=[CH:15][C:14]([O:17][C:18](=[O:20])[CH3:19])=[C:13]([O:21][CH3:22])[CH:12]=2)=[O:8])[CH2:5][CH2:4]S1.C(N)[C:24]1[CH:29]=[CH:28]C=[CH:26][CH:25]=1>C1COCC1.C(OCC)C>[C:18]([O:17][C:14]1[CH:15]=[CH:16][C:11]([CH2:10][O:9][C:7](=[O:8])[NH:6][CH2:5][C:4]2[CH:28]=[CH:29][CH:24]=[CH:25][CH:26]=2)=[CH:12][C:13]=1[O:21][CH3:22])(=[O:20])[CH3:19]Compound VII (339 mg, 0.993 mmol) was dissolved in anhydrous THF (5 mL). To the stirred, yellow solution was added at room temperature a solution of benzylamine (160 mg, 163 pt, 1.5×0.993 mmol) in anhydrous THF (5 mL), After being stirred overnight, the reaction solution was diluted with diethyl ether and extracted with 1N HCl, water and saturated NaCl. The organic phase was dried over anhydrous MgSO4, filtered and concentrated. Purification by column chromatography on silica gel eluting with hexanes/ethyl acetate (7:3-1:1, v/v) afforded 23 mg (7%) of 8 as a clear oil: Rf=0.30 (hexanes/ethyl acetate, 1:1, v/v); 1HNMR (CDCl3) δ 7.34-7.25 (m, 5H), 6.99 (d, 3J=8.0 Hz, 1H), 6.96 (s, 1H), 6.92 (d, 3J=8.1 Hz, 1H), 5.09 (s, 2H), 5.04 (bs, 1H, NH), 4.38 (d, 3J=6 Hz, 2H), 3.81 (s, 3H) and 2.29 (s, 3H). While the synthesis proceeded in excellent yield, product isolation was compromised by decomposition during work-up.
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