反应详情

A mixture of 4-nitroacetophenone (1.65 g, 10.0 mmol), p-toluenesulfonic acid (172 mg, 1.00 mmol) and ethylene glycol (1.7 mL, 30 mmol) in dry toluene (20 mL) was heated at reflux with a Dean-Stark apparatus under nitrogen for 24 h. The mixture was allowed to cool to room temperature and the solvent was evaporated in vacuo. The residue was taken up in ether (20 mL) and the solution was washed with saturated sodium bicarbonate solution (2×10 mL) and brine (1×10 mL), then dried (Na2SO4) and concentrated under reduced pressure. Recrystallisation from ether and hexanes afforded 2-(4-nitrophenyl)-2-methyl-1,3-dioxolane (25) as a pale yellow crystals (1.52 g, 73%; yield based from the first crop of crystals). 1H nmr (300 MHz, CDCl3) 1.66 (s, 3H, CH3), 3.71-3.83 (m, 2H, OCH2), 4.02-4.13 (m, 2H, OCH2), 7.63-7.73 (d, J=8.8 Hz, 2H, 2×ArH), 8.16-8.26 (d, J=8.8 Hz, 2H, 2×ArH).

1. temperaturewas heated
2. temperatureat reflux with a Dean-Stark apparatus under nitrogen for 24 h
3. customthe solvent was evaporated in vacuo
4. washthe solution was washed with saturated sodium bicarbonate solution (2×10 mL) and brine (1×10 mL)
5. dry with materialdried (Na2SO4)
6. concentrationconcentrated under reduced pressure
7. customRecrystallisation from ether and hexanes