反应详情

Benzofurazan-5-carboxylic acid (1 g, 5.6 mmol) was suspended with stirring in 15 mL dichloromethane to which was added carbonyl diimidazole (0.90 g, 5.6 mmol). Gas evolved and the resulting solution was stirred for 40 minutes at which time piperidine (0.5 g, 5.9 mmol) was added with stirring. The reaction solution was concentrated onto silica and product was eluted with hexanelethyl acetate (3:1). Recrystallization from 2-propanol/hexane (1:10) yielded 1-(benzofurazan-5-ylcarbonyl)piperidine (0.94 g, 69%) as a yellow solid with, m.p. 94.5-96.5° C. IR: 2938, 2855, 1620, 1612, 1528, 1487, 1435, 1257, 1233, 1018, 1000, 852, 811, and 747 cm−1. 1H NMR (500 MHz): δ 7.10-7.80 (3H, br s); 3.72 (2H br s); 3.39 (2H, br s); 1.72 (4H, br s); and 1.54 ppm (2H, br s).

1. additionwas added
2. concentrationThe reaction solution was concentrated onto silica and product
3. washwas eluted with hexanelethyl acetate (3:1)
4. customRecrystallization from 2-propanol/hexane (1:10)