[F:1][C:2]1[C:3]([CH:14]=[N:15][OH:16])=[CH:4][C:5]2[C:9]([CH3:11])([CH3:10])[O:8][B:7]([OH:12])[C:6]=2[CH:13]=1.C1C(=O)N([Cl:24])C(=O)C1>CN(C=O)C>[F:1][C:2]1[C:3]([C:14]([Cl:24])=[N:15][OH:16])=[CH:4][C:5]2[C:9]([CH3:11])([CH3:10])[O:8][B:7]([OH:12])[C:6]=2[CH:13]=1To a solution of the crude compound 6-fluoro-1-hydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborole-5-carbaldehyde oxime (205 mg, 0.92 mmol) in DMF (4.0 mL) at rt was added NCS (147 mg, 1.1 mmol). The reaction mixture was stirred at 45° C. for 3 h. The mixture was cooled to rt, poured into ice-water and extracted with DCM (60 mL×3). The organic layer was washed with brine, dried over Na2SO4, filtered and concentrated under reduced pressure to give the crude compound 6-fluoro-N,1-dihydroxy-3,3-dimethyl-1,3-dihydrobenzo[c][1,2]oxaborole-5-carbimidoyl chloride as colorless oil. It was used in next step without further purification.
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