2-Bromo-4'-nitroacetophenone → Ethyl 2-amino-5-(4-nitrophenyl)-1H-pyrrole-3-carboxylate

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Reaction Steps

In a dry three-necked flask, under argon, 75 ml of abs. ethanol and 6.5 g (390 mmol) of 2-amidino-acetic acid ethyl ester hydrochloride [for preparation see: Liebigs Ann. Chem., 1895 (1977)] are cooled to 0-5° C. and 2.65 g (390 mmol) of sodium ethanolate are added thereto. Then 5 g (195 mmol) of 2-bromo-1-(4-nitro-phenyl)-ethan-1-one are added and the reaction mixture is allowed to come to RT and then stirred for 48 hours. The reaction mixture is then partitioned between water and ethyl acetate. The ethyl acetate phase is washed three times with water and once with saturated NaCl solution, dried and filtered and the filtrate is concentrated by evaporation. The red-brown residue is suspended in hexane and the title compound precipitates in the form of the crude product (purity 93%), which is used for the next step without further purification; MS: (M)+ =275.

Provenance & Evidence