1,2-Dibromoethane → Ethyl 1-(4-bromo-2-methylphenylaminocarbonyl)cyclopropanecarboxylate

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Reaction Steps

Into a 100 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, 1.7 milliliters (20.0 mmol) of 1,2-dibromoethane and 0.33 grams (0.83 mmol) of Aliquat® 336 in 25 milliliters of methylene chloride. The resulting solution was stirred at ambient temperature under a nitrogen atmosphere as 0.2 milliliters of water and 4.60 grams (33.0 mmol) of potassium carbonate was added to the reaction flask. The resulting mixture was stirred for a total of 8 days and the reaction was monitored by high pressure liquid chromatography throughout this period (after one day, an additional 0.2 milliliters of water was added and, after 2 days, an additional 0.33 grams (0.83 mmol) of Aliquat® 336 and 1.7 milliliters (20.0 mmol) of 1,2-dibromoethane were added). After the 8 day reaction period, the reaction mixture was diluted with 125 milliliters of water and extracted with methylene chloride. The combined organic extracts were washed with 125 milliliters of 3N aqueous HCl and 125 milliliters of saturated aqueous sodium bicarbonate. After drying over anhydrous magnesium sulfate and evaporation, a yellow solid residue was obtained which was flash chromatographed on silica gel with an 85:15 volume/volume hexane-ethyl acetate eluent to give 4.20 grams (12.9 mmol) of ethyl 1-(4-bromo-2-methylphenylaminocarbonyl)cyclopropanecarboxylate as a pale yellow solid having a melting point of 87.5° C.-89.0° C. The total yield was 80 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