[Br:1][C:2]1[CH:3]=[CH:4][C:5]([OH:10])=[C:6]([CH:9]=1)[CH:7]=O.[C:11]([O:15][C:16](=[O:19])[NH:17][NH2:18])([CH3:14])([CH3:13])[CH3:12].C(O)(=O)C.C(O[BH-](OC(=O)C)OC(=O)C)(=O)C.[Na+]>C(Cl)Cl>[C:11]([O:15][C:16]([NH:17][NH:18][CH2:7][C:6]1[CH:9]=[C:2]([Br:1])[CH:3]=[CH:4][C:5]=1[OH:10])=[O:19])([CH3:14])([CH3:13])[CH3:12]A solution of 5-bromo-2-hydroxybenzaldehyde (10 g g 50 mmol), tert-butylcarbazate (6.7 g, 52 mmol) and acetic acid (3 mL, 52 mmol) in CH2Cl2 (200 mL) was stirred under N2 atmosphere for 60 min at RT. Then sodium triacetoxyborohydride (34 g, 159 mmol) was added portion wise and the resulting mixture was stirred at RT overnight. The reaction was quenched with 2 M HCl (100 mL) and stirred at RT for 1 h. The reaction mixture was partitioned between water (100 mL) and CH2Cl2 (250 mL). The organic layer was washed with sat. NaHCO3 and brine (100 mL each), dried (MgSO4) and evaporated to dryness to give hydrazine 1 as a white solid, 13 g (82%).
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