2-Methyl-4-nitroindole synthesis
- Product Name:2-Methyl-4-nitroindole
- CAS Number:3484-10-4
- Molecular formula:C9H8N2O2
- Molecular Weight:176.17
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In a 125 mL Erlenmeyer flask, 3-nitroaniline (1.00 g, 7.24 mmol) and acetone (0.74 mL, 0.59 g, 10 mmol) were dissolved in 20 mL of dimethyl sulfoxide (DMSO). Potassium tert-butoxide (1.95 g, 17.4 mmol) was added to the solution and the reaction mixture was stirred at room temperature for 2 h until LC-MS analysis showed that most of the feedstock had been consumed. Upon completion of the reaction, the reaction was quenched by the addition of 85 mL of saturated ammonium chloride solution, followed by extraction with ethyl acetate (3 × 75 mL). The organic phases were combined, washed with 60 mL of water, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by fast column chromatography on silica gel, the eluent being a hexane solution of 6-50% ethyl acetate, to afford the target compound 2-methyl-4-nitroindole (0.56 g, 44% yield). The structure of the product was confirmed by 1H NMR (DMSO-d6): δ 11.85 (br.s, 1H), 7.99 (dd, J = 8.1, 1.0 Hz, 1H), 7.74 (dt, J = 8.0, 0.8 Hz, 1H), 7.19 (t, J = 8.0 Hz, 1H), 6.80 (t, J = 0.9 Hz, 1H), 2.49 (d , J = 0.8 Hz, 3H).
![Ethanamine, N-[(3,5-dichlorophenyl)methylene]-2,2-diethoxy-](/CAS/20210305/GIF/1000210-73-0.gif)
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Yield: 25% ， 10%
Reaction Conditions:
with potassium ethoxide in dimethyl sulfoxide;N,N-dimethyl-formamide at 0; for 72 h;Reflux;
Steps:
2.2. 2-Methyl-4-nitroindole (410)
Without further purification, the imidate ester 3 was used in the reaction: in a 100 mL flask, 3.2 g (14.4 mmol) imidate ester in 12.0 mL anhydrous DMSO were treated with 3.0 mL diethyl oxalate (21.7 mmol, d = 1.076) in 8 mL anhydrous DMF and 1.58 g (18.8 mmol) potassium ethoxide at 0 °C. After 72 h at refluxing, the cooled red reaction mixture was poured onto ice/water and the nitro-indole separated as a red amorphous solid, which was collected and dried under vacuum at 30 °C. Subsequently it was purified by flash chromatography (ethyl acetate/n-hexane 1:1). Yield 25%; mp 192-94 °C; rf 0.63 (ethyl acetate/n-hexane 1:1); 1H NMR (DMSO-d6) δ 2.48 (s, 3H, CH3), 6.79 (d, 1H, J3,7 = 0.76, 3-H), 7.18 (dd, 1H, J6,7 = 8.01 Hz, J6,5 = 8.01 Hz, 6-H), 7.74 (dd, 1H, J7,6 = 8.01 Hz, J7,5 = 0.76 Hz, 7-H), 7.98 (dd, 1H, J5,6 = 8.01 Hz, J5,7 = 0.76 Hz, 5-H), 11.98 (br s, 1H, NH).
References:
Ferlin, Maria Grazia;Conconi, Maria Teresa;Urbani, Luca;Oselladore, Barbara;Guidolin, Diego;Di Liddo, Rosa;Parnigotto, Pier Paolo [Bioorganic and Medicinal Chemistry,2011,vol. 19,# 1,p. 448 - 457] Location in patent:supporting information; experimental part
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