[F:1][C:2]([F:14])([F:13])[C:3]1[CH:8]=[CH:7][C:6]([CH2:9][C:10](Cl)=[O:11])=[CH:5][CH:4]=1.C[Si]([CH:19]=[N+:20]=[N-:21])(C)C.C(OCC)C>C1COCC1.C(#N)C>[N+:20](=[CH:19][C:10](=[O:11])[CH2:9][C:6]1[CH:7]=[CH:8][C:3]([C:2]([F:14])([F:13])[F:1])=[CH:4][CH:5]=1)=[N-:21]Under an argon atmosphere, p-trifluoromethylphenylacetyl chloride (52) prepared above was dissolved in THF (2 mL) and acetonitrile (2 mL), and cooled to 0° C. To this was slowly added a solution of trimethylsilyldiazomethane in diethyl ether (2.0 M, 4.00 mL, 8.00 mmol), which was stirred overnight (20 hours) after warming up to room temperature. After being concentrated under reduced pressure, the residue was purified by silica gel flash column chromatography (n-hexane/diethyl ether═1/1) to give 1-diazo-3-[4-(trifluoromethyl)phenyl]propan-2-one (53) as a pale yellow oily substance (666 mg, 2.92 mmol, 72.9%, 2 steps).
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