反应详情

温度

120 °C

2,2-Dimethyl-7-nitro-2H-benzo[b]pyran (40.00 g, the preparation of which was disclosed in U.K. Pat. No. 1,548,222), glacial acetic acid (200 ml), acetic anhydride (120 ml) and electrolytic iron powder (88 g) were stirred and heated at 120° C. for 16 hours. Dilution with water, extraction via chloroform, followed by washing of the organic layer with water and sodium bicarbonate solution, drying evaporation etc., gave a crude gum which was chromatographed on a silica gel column using ethyl acetate--60°--80° petroleum ether mixtures in a gradient elution technique. Fractions homogeneous by TLC were combined and recrystallised from 60°-80° petroleum ether to give 7-acetamido-2,2-dimethyl-2H-benzo[b]pyran (5.27 g) as white needles of mp 80°-81° C.; nmr (CDCl3) δ 1.39 (6H), 2.12 (3H), 5.48 (1H, d, J=10), 6.21 (1H, d, J=10), 6.76-7.34 (3H, m), 8.95 (1H). Anal. Calcd for C13H15NO2 ; C, 71.87; H, 6.96; N, 6.45. Found: C, 72.00; H, 7.11; N, 6.23%.

1. extractionDilution with water, extraction via chloroform
2. washby washing of the organic layer with water and sodium bicarbonate solution
3. customdrying
4. customevaporation etc.
5. customgave a crude gum which
6. customwas chromatographed on a silica gel column
7. customethyl acetate--60°--80° petroleum ether
8. washmixtures in a gradient elution technique
9. customrecrystallised from 60°-80° petroleum ether