Reaction Steps
To a solution of hydroxyamine 55 (0.80 g, 2 mmol) in anhydrous ethyl alcohol (5 mL) and toluene (20 mL) was added 1-methyl-2-pyrrolecarboxaldehyde (66) (0.22 g, 2 mmol) and Na2SO4 (0.30 g). The resulting mixture was heated at reflux for 48 h. The mixture was diluted with dichloromethane (100 mL) and dried (MgSO4), and the solvent was removed with a rotary evaporator. The crude product was purified by flash chromatography with 9:1 ethyl acetate/methanol as the eluant to obtain 0.40 g (0.8 mmol, 40%) of 77 as a light yellow solid: mp 173°-175° C.; IR (CH2Cl2) 3440, 2940, 1695, 1622, 1575, 1470, 1300, 1212, 1100 cm-1 ; 1H NMR (CDCl3) δ 1.10 (d, J=6.2 Hz, 3H), 1.22 (d, J=6.2 Hz, 3H), 2.26 (s, 6H), 3.31 (s, 3H), 3.55 (t, J=4.8 Hz, 2H), 3.71 (s, 3H), 4.11-4.20 (m, 2H), 4.94 (septet, J=6.2 Hz, 1H), 5.08 (s, 1H), 6.30-7.98 (m, 9H); 13C NMR (CDCl3) δ 19.17, 19.32, 22.01, 22.23, 34.34, 39.98, 58.79, 62.76, 67.04, 70.71, 102.63, 103.45, 109.56, 117.39, 118.95, 121.24, 124.21, 125.59, 128.01, 128.23, 129.62, 145.20, 146.02, 148.30, 149.91, 167.12, 167.60; mass spectrum, m/e (relative intensity) 495 (M+, 3.1), 481 (15.5), 296 (100), 254 (86.1), 184 (90.2), 108 (48.3); high resolution mass spectrum, m/e 495.2362 (calcd. for C27H33N3O6, 495.2369).
