反应详情

A solution of 2-nitrobenzene-1,4-diamine (2.00 g; 13.1 mmol), di-tert-butyl dicarbonate (3.14 g, 14.4 mmol), and DIPEA (2.6 mL; 14.9 mmol) in dioxane (40 mL) was heated at reflux for 40 min, then allowed to cool to room temperature. The mixture was concentrated under reduced pressure and taken up in EA (100 mL). The EA solution was washed with water and the aqueous phase extracted with EA. The combined organic layers were washed with saturated aqueous sodium bicarbonate and brine, dried over magnesium sulfate, and concentrated under reduced pressure to give tert-butyl 3-amino-4-nitrophenylcarbamate in quantitative yield as a brown solid. To a stirred solution of tert-butyl 3-amino-4-nitrophenylcarbamate (2.74 g; 10.8 mmol) in anhydrous THF (50 mL) was added sodium hydride (0.868 g of a 60 wt % dispersion in oil, 21.7 mmol) in portions over 10 min. The mixture was stirred for a further 5 min at room temperature and then iodoethane (950 μL; 11.9 mmol) was added. The solution was stirred for 20 hr, water (1 mL) was added, and the solution concentrated under reduced pressure. The residue was partitioned between EA and water and the phases separated. The aqueous phase was extracted twice with EA and the combined organic phases washed with water, saturated aqueous sodium bicarbonate and brine. The organic solution was dried over magnesium sulfate and concentrated under reduced pressure to give a mixture of mono- and di-ethylated products (2.18 g). This was purified by silica gel column chromatography eluting with 1:4 EA/hexanes to give tert-butyl 4-amino-3-nitrophenyl(ethyl)carbamate (0.534 g) as an orange solid. A solution of tert-butyl 4-amino-3-nitrophenyl(ethyl)carbamate (0.514 g; 1.83 mmol) in 4M hydrogen chloride in dioxane (10 mL) was stirred at ambient temperature for 3 hr. The solvent was removed under reduced pressure and the residue dissolved in water. The pH was adjusted to 10 with 1M aqueous sodium hydroxide and the aqueous phase was extracted three times with EA. The combined organic extracts were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure to give N1-ethyl-3-nitrobenzene-1,4-diamine (0.311 g) as a purple solid. N1-Ethyl-3-nitrobenzene-1,4-diamine (0.208 g; 1.38 mmol) was dissolved in acetonitrile (10 mL) and N,N-diethylglycine sodium salt (0.192 g; 1.25 mmol) and DEPBT (0.375 g; 1.25 mmol) were added, followed by triethylamine (577 μL; 4.14 mmol). The mixture was stirred at room temperature for 8 hr; and then further quantities of N,N-diethylglycine sodium salt (0.192 g; 1.25 mmol), DEPBT (0.375 g; 1.25 mmol), and triethylamine (577 μL; 4.14 mmol) were added and stirring continued for 63 hr. Solids were removed by filtration and the filtrate concentrated under reduced pressure. Water was added to the residue and the pH was adjusted to 10 with saturated aqueous sodium bicarbonate. This solution was extracted three times with EA, and the organic extracts combined, washed with water and brine, dried over magnesium sulfate, and concentrated under reduced pressure to give N-(4-amino-3-nitrophenyl)-2-(diethylamino)-N-ethylacetamide (0.303 g) as a brown oil. A solution of N-(4-amino-3-nitrophenyl)-2-(diethylamino)-N-ethylacetamide (0.092 g; 0.31 mmol) in ethanol (5 mL) was hydrogenated at atmospheric pressure with 10% palladium on carbon (11 mg) at room temperature for 22 hr. The mixture was filtered through diatomaceous earth, washing with ethanol, and the filtrate was concentrated under reduced pressure to give N-(3,4-diaminophenyl)-2-(diethylamino)-N-ethylacetamide in quantitative yield as a brown oil.

1. stirringstirring
2. waitcontinued for 63 hr
3. customSolids were removed by filtration
4. concentrationthe filtrate concentrated under reduced pressure
5. additionWater was added to the residue
6. extractionThis solution was extracted three times with EA
7. washwashed with water and brine
8. dry with materialdried over magnesium sulfate
9. concentrationconcentrated under reduced pressure