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A mixture of 30.0 grams (0.10 mole) of ethyl 3-[(4-bromo-2-methylphenyl)amino]-3oxopropanoate, 51.58 grams (0.25 mole) of 1,3-dicyclohexylcarbodiimide, 100 milliliters of benzene and 100 milliliters of dimethyl sulfoxide was stirred at ambient temperature and a solution of 4.9 grams (0.05 mole) of anhydrous phosphoric acid in 10 milliliters of dimethyl sulfoxide added dropwise. After a few minutes an exothermic reaction occurred with separation of a white solid and an increase in temperature from 25° C. to 35° C. The reaction mixture was then stirred for an approximate 16-hour period at ambient temperature. The mixture was then diluted with 500 milliliters of ethyl acetate and by-product 1,3-dicyclohexylurea removed by filtration. The filtrate was washed with several portions of water, dried over MgSO4, filtered and freed of solvent under reduced pressure to give a yellow solid. This was crystallized from ethyl acetate-hexane (1:1) to give 15.8 grams (0.04 mole) of ethyl 3 -[(4-bromo-2-methylphenyl)amino]-2-(dimethylsulfuranylidene)-3-oxopropanoate having a melting point of 143° C.-150° C. Recrystallization of a small sample gave a white solid of melting point 146° C.-149° C. Elemental analysis of the product indicated the following:

1. customAfter a few minutes an exothermic reaction
2. customoccurred with separation of a white solid
3. temperaturean increase in temperature from 25° C. to 35° C
4. stirringThe reaction mixture was then stirred for an approximate 16-hour period at ambient temperature
5. additionThe mixture was then diluted with 500 milliliters of ethyl acetate and by-product 1,3-dicyclohexylurea
6. customremoved by filtration
7. washThe filtrate was washed with several portions of water
8. dry with materialdried over MgSO4
9. filtrationfiltered
10. customto give a yellow solid
11. customThis was crystallized from ethyl acetate-hexane (1:1)