反应详情

温度

55 °C

5,6-Dihydro-2H-pyran-2-one (1.0 g, 10.2 mmol) was dissolved in 3 ml of a 33% solution of methylamine in ethanol and heated to 55° C. overnight. The solvent was evaporated, the residue dissolved in methanol (20 ml) and conc. HCl (20 ml) and the mixture heated at 95° C. for 2.5 h. The mixture was evaporated to dryness, the residue dissolved in THF (20 ml), dichloromethane (20 ml) and triethylamine (3 ml) and a solution of [2,1,3]-benzoxadiazole-5-carboxylic acid chloride (2.0 g, 11 mmol), in dichloromethane (5 ml), added. After stirring the mixture for 0.75 h, the mixture was washed with 1N HCl and conc. NaHCO3 solution, dried over sodium sulfate, and concentrated under vacuum. The residue was purified on a silica gel column using ethyl acetate/hexane/dichloromethane (70:20:10), to give N-methyl-N-(2-oxotetrahydro-2H-pyran-4-yl)-[2,1,3]-benzoxadiazole-5-carboxamide as white solid after crystallization from dichloromethane/methanol (0.21 g). Mp=169-171° C., 1H NMR (300 MHz, CDCl3, rotamers) δ 7.97 (d, J=9.0 Hz, 1H); 7.90 (s, 1H); 7.40 (d, J=9.0 Hz, 1H); 5.10-4.40 (m, 3H); 3.01 (s, 3H); 3.00-2.74 (m, 2H) and 2.60-2.10 ppm (s, 2H).

1. customThe solvent was evaporated
2. dissolutionthe residue dissolved in methanol (20 ml)
3. temperatureconc. HCl (20 ml) and the mixture heated at 95° C. for 2.5 h
4. customThe mixture was evaporated to dryness
5. dissolutionthe residue dissolved in THF (20 ml)
6. washthe mixture was washed with 1N HCl and conc. NaHCO3 solution
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated under vacuum
9. customThe residue was purified on a silica gel column