[F:1][C:2]([F:11])([F:10])[C:3]1[CH:7]=[C:6]([CH2:8]O)[O:5][N:4]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(Cl)(Cl)(Cl)[Cl:32]>ClCCl>[Cl:32][CH2:8][C:6]1[O:5][N:4]=[C:3]([C:2]([F:11])([F:10])[F:1])[CH:7]=1A solution of 3-trifluoromethyl-5-hydroxymethylisoxazole [(700 mg, 4.2 mmol) See K. Tanaka et al, Bull. Chem. Soc. Jpn., 57, 2184 (1984)] and triphenylphosphine (1.43 g, 5.4 mmol) in carbontetrachloride (50 ml) and dichloromethane (20 ml) is heated at reflux for 6 hours. The reaction mixture is then cooled to room temperature and passed through a silica gel plug. Concentration affords in 82% yield the desired 5-chloromethyl-3-trifluoromethylisoxazole of sufficient purity for the following step (Example 24).
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