[Cl:1][C:2]1[N:7]=[N:6][C:5]([CH2:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[O:15]C)=[CH:4][CH:3]=1.B(Br)(Br)Br.CC(C)=O>ClCCl>[Cl:1][C:2]1[N:7]=[N:6][C:5]([CH2:8][C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=2[OH:15])=[CH:4][CH:3]=12-(6-Chloro-3-pyridazinylmethyl)anisole (prepared as described in Example 33(c)) (2.35 g) was dissolved in dry dichloromethane (20 ml) and cooled with stirring to -50°. Boron tribromide (3 ml) was then added dropwise, and the solution was allowed to warm to room temperature. After 0.5 hours the orange reaction mixture was poured into ice/water (200 ml) and acetone added to dissolve the precipitated solid. The mixture was extracted with dichloromethane, the organic extracts were separated, washed with water, dried, and evaporated. The residue was recrystallised from ethyl acetate and petroleum spirit to give 2-(6-chloro-3-pyridazinylmethyl)phenol (1.75 g, 80%), m.p. 132°-132.5°.
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