22568-07-6

75-52-5

89-98-5

22568-07-6

GENERAL METHOD: Hexylamine (20 mg, 0.2 mmol) was added to a solution of toluene (4 mL) containing 3a (212 mg, 2.0 mmol), silica gel (200 mg) and nitromethane (134 mg, 2.2 mmol). The reaction mixture was stirred at 90 °C for 4 hours. After completion of the reaction, the silica gel was removed by filtration and the filter cake was washed with toluene. The filtrate was concentrated under reduced pressure at 40 °C to give the crude product. The crude product was purified by silica gel column chromatography using heptane-acetone (5:1, v/v) as eluent to afford the target compound 5a (268 mg, 90% yield).