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82 g of 2-(4-Methoxy-phenyl)-4,5-dimethyl-oxazole 3-oxide are dissolved in 400 ml of chloroform, 37.4 ml of phosphorus oxychloride are added and the mixture is, under reflux, heated at the boil for 30 minutes. The reaction mixture is cooled to 0° C., the pH is made slightly alkaline using ammonia and the mixture is extracted three times with in each case 100 ml of ethyl acetate. The combined organic phases are washed with water and dried over MgSO4, and the solvent then removed under reduced pressure. The residue is purified on silica gel using the mobile phase n-heptane:ethyl acetate=80:1=>5:1. This gives 46.3 g of 4-chloromethyl-2-(4-methoxy-phenyl)-5-methyl-oxazole as a yellow solid. C12H12ClNO2 (237.69), MS (ESI)=238 (M+H+), Rf (n-heptane:ethyl acetate)=7:3)=0.45.

1. temperatureunder reflux
2. temperatureheated at the boil for 30 minutes
3. extractionthe mixture is extracted three times with in each case 100 ml of ethyl acetate
4. washThe combined organic phases are washed with water
5. dry with materialdried over MgSO4
6. customthe solvent then removed under reduced pressure
7. customThe residue is purified on silica gel using the mobile phase n-heptane