Triethylamine → (3-Fluoro-4-nitrophenyl)carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

Diphenylphosphorylazide (5.5 mmol, 1.5 g) was added to a solution of 3-fluoro-4-nitrobenzoic acid (5.4 mmol, 1 g) and triethylamine (5.6 mmol, 0.8 mL) in a 1:1 mixture of tert-butyl alcohol/dioxane (60 mL). The reaction mixture was refluxed for 2 days at 95° C. and the solvent was evaporated to give an oily residue. The residue was taken up in ethyl acetate (100 mL) and washed with 10% citric acid, 1N NaOH, brine and H2O. Evaporation of solvent afforded an orange residue that was subsequently purified by flash chromatography eluting with ethyl acetate/hexane to afford (tert-butoxy)-N-(3-fluoro-4-nitrophenyl)carboxamide (1.75 mmol, 0.45 g, yield 32%). 3-Fluoro-4-nitroaniline (0.36 g, 2.3 mmol) was isolated as a byproduct. Treatment of (tert-butoxy)-N-(3-fluoro-4-nitrophenyl)carboxamide with trifluoroacetic acid in methylene chloride afforded additional 3-fluoro-4-nitroaniline.

Provenance & Evidence