反応 #487584

反応方程式

8,9-dihydro-5H-benzo[7]annulen-7(6H)-one

sulfuric acid

nitric acid

→

2-nitro-8,9-dihydro-5H-benzo[7]annulen-7(6H)-one

収率 40.0%

溶媒

nitromethane

反応条件

後処理

1. 1
   workup.ADDITIONThe addition
2. 2
   温度to maintain the internal reaction temperature below 5° C
3. 3
   workup.ADDITIONAfter the addition
4. 4
   その他the resulting solution was transferred into an addition funnel
5. 5
   workup.ADDITIONAfter the addition
6. 6
   workup.STIRRINGthe mixture was stirred for additional 30 min
7. 7
   その他Then the mixture was transferred to a separatory funnel
8. 8
   その他where the layers were separated
9. 9
   抽出The aqueous layer was extracted with ethyl acetate (3×80 mL)
10. 10
    洗浄The combined layers were washed with cold water, sat. NaHCO3 solution and brine
11. 11
    乾燥After being dried (MgSO4)
12. 12
    ろ過filtered
13. 13
    濃縮concentrated
14. 14
    その他the residue was purified by flash column chromatography on silica gel (hexanes/EtOAc=3:1 to 2:1)
15. 15
    その他to afford
16. 16
    その他was then purified by recrystallization from MTBE (tert-butyl methyl ether, 180 mL)

実験手順

To a solution of cold (0° C.) concentrated sulfuric acid (15 mL) was added 70% nitric acid (15 mL) dropwise over 30 min. The addition was controlled to maintain the internal reaction temperature below 5° C. After the addition, the resulting solution was transferred into an addition funnel and was added dropwise to a solution of 8,9-dihydro-5H-benzo[7]annulen-7(6H)-one (14 g, 87.5 mmol) in nitromethane (80 mL) at 0° C. over a period of 40 min. After the addition, the reaction mixture was stirred at 0° C. for 2 h. Then ice water (˜80 mL) was added to the reaction mixture, and the mixture was stirred for additional 30 min. Then the mixture was transferred to a separatory funnel where the layers were separated. The aqueous layer was extracted with ethyl acetate (3×80 mL). The combined layers were washed with cold water, sat. NaHCO3 solution and brine. After being dried (MgSO4), filtered, and concentrated, the residue was purified by flash column chromatography on silica gel (hexanes/EtOAc=3:1 to 2:1) to afford the mixture of nitro regioisomers (˜15 g), which was then purified by recrystallization from MTBE (tert-butyl methyl ether, 180 mL) to yield 7.3 g of 2-nitro-8,9-dihydro-5H-benzo[7]annulen-7(6H)-one (40% yield) as a yellow solid: 1H NMR (300 MHz, CDCl3) δ: 8.10-8.06 (m, 2H), 7.40-7.37 (m, 1H), 3.04-3.00 (m, 4H), 2.67-2.65 (m, 4H); LC-MS: 206 (M+H)+.

出典