Triethylamine → 2-(2-t-Butyl-7-chloro-5-fluorobenzoxazol-4-yl)-5-trifluoromethylpyridazin-3-one

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Reaction Steps

Step 4 Under nitrogen atmosphere 2-(2-amino-4-chloro-6-fluoro-3-hydroxyphenyl)-5-trifluoromethylpyridazin-3-one from step 3, trimethylacetyl chloride (0.17 g), triethylamine (0.14 g) and pyridinium p-toluenesulfonate in m-xylene(30 ml) was heated at reflux temperature overnight. The mixture was allowed to cool to ambient temperature and partitioned between ethyl acetate and brine. The organic phase was dried over anhydrous sodium sulfate and concentrated to an oil. The crude product was purified by column chromatography on silica gel eluted with ethyl. acetate-hexane (1:8) to afford 2-(2-t-butyl-7-chloro-5-fluorobenzoxazol-4-yl)-5-trifluoromethylpyridazin-3-one (0.26 g) as a pale yellow solid.

Provenance & Evidence