[F:1][C:2]1[CH:9]=[C:8]([F:10])[CH:7]=[CH:6][C:3]=1[CH2:4]Br.[Mg].[Br-].CON(C)[C:16]([C:18]1[CH:23]=[CH:22][C:21]([I:24])=[CH:20][CH:19]=1)=[O:17]>CCOCC>[F:1][C:2]1[CH:9]=[C:8]([F:10])[CH:7]=[CH:6][C:3]=1[CH2:4][C:16]([C:18]1[CH:23]=[CH:22][C:21]([I:24])=[CH:20][CH:19]=1)=[O:17]2,4-Difluorobenzyl bromide (23.7 ml, 0.114 mol) was added dropwise to a stirred mixture of magnesium turnings (8.1 g, 0.183 mol) in dry ether (300 ml) under nitrogen. The mixture was warmed initially until reaction started, and thereafter the bromide was added at such a rate as to maintain a gentle reflux. After 1 hour, the resulting solution of the Grignard reagent was added dropwise at −78° C. to a solution of O,N-dimethyl-4-iodobenzenehydroxamic acid [see step (a)] (45.7 g, 0.157 mol) in dry ether (300 ml), and the mixture was allowed to warm slowly to room temperature overnight. The mixture was partitioned between saturated aqueous ammonium chloride and ethyl acetate, and the organic solution was separated, dried (MgSO4) and concentrated under reduced pressure, to give the title compound as a white solid, 38.71 g (69%), which was characterised by 1H-N.M.R. spectroscopy.
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