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3.33 g (21.7 mmol) of 5-cyclopropylisoxazole-4-carboxylic acid and 25 ml of thionyl chloride were refluxed for 90 minutes and after the thionyl chloride was evaporated in vacuo, the residue was azeotroped twice with toluene. 4.0 g (21.7 mmol) of 4-bromo-3-methyl-aniline were dissolved in 125 ml of dry dichloromethane, cooled to 0° C. and the acid chloride and 2.4 g (30 mmol) of pyridine each dissolved in 10 ml of dichloromethane, were added dropwise simultaneously. After stirring for thirty minutes at 0° C., the reaction mixture was washed 3 times with 75 ml of brine, dried over MgSO4 and the dichloromethane was removed in vacuo to yield a brown oil. Flash column chromatography (2% MeOH, 98% CH2Cl2) yielded a pale brown oil which crystallized upon standing. Crystallization from ethanol/water yielded the desired product as cream needles melting at 133°-135° C.

1. customafter the thionyl chloride was evaporated in vacuo
2. customthe residue was azeotroped twice with toluene
3. additionwere added dropwise simultaneously
4. washthe reaction mixture was washed 3 times with 75 ml of brine
5. dry with materialdried over MgSO4
6. customthe dichloromethane was removed in vacuo
7. customto yield a brown oil
8. customcrystallized
9. customCrystallization from ethanol/water