Dimethylformamide → Ethyl 1-(4-bromo-2-methylphenylaminocarbonyl)cyclopropanecarboxylate

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Reaction Steps

Into a 250 milliliter three-necked round-bottom reaction flask equipped with a mechanical stirrer, thermometer and nitrogen inlet and outlet was added 5.0 grams (17.0 mmol) of ethyl 3-[(4-bromo-2-methylphenyl)amino]-3-oxopropanoate prepared as in Example A, 5.73 grams (42.0 mmol) of anhydrous potassium carbonate, 20 milliliters of anhydrous dimethylformamide and 1.7 milliliters (20.0 mol) of 1,2-dibromoethane. The resulting mixture was stirred at ambient temperature under a nitrogen atmosphere and irradiated with ultra sound waves using a Bransonic 52 ultrasonic cleaning bath for a period of 4.25 hours. Ice was added to maintain the temperature of the bath between 26° C. and 31° C. After this period, high pressure liquid chromatographic analysis showed the reaction to be complete. The product was isolated by diluting with methylene chloride, filtering off the solids and concentrating under reduced pressure to give a yellow solid. Chromatography on silica gel with a 3:1 volume/volume hexane-ethyl acetate eluent provided 4.58 grams (14.0 mmol) of ethyl 1-(4-bromo-2-methylphenylaminocarbonyl)cyclopropanecarboxylate as a pale yellow solid having a melting point of 87° C.-89° C. The total yield was 87 percent based on a 96.7 weight percent assay of the starting ethyl 3-[(4-bromo-2-methylphenyl)amino]-3-oxopropanoate. NMR analysis of the product indicated the following:

Provenance & Evidence