A mixture of 2-(3-bromobenzoyl)-3-hydroxypyridine 1-oxide (2.13 g), t-butylhydrazine hydrochloride (3.03 g), triethylamine (3.5 mL) and ethanol (50 mL) was refluxed for 2 hours. The reaction mixture was then poured into a saturated aqueous saline solution, and subjected to extraction with ethyl acetate. The extract was washed with a saturated aqueous saline solution, and dried (sodium sulfate), followed by evaporating the solvent under reduced pressure. The residue was purified by means of a silica gel column (ethyl acetate--hexane) to afford (E)-2-(3-bromo-t-butylhydrazonobenzyl)-3-hydroxypyridine 1-oxide (0.68 g) and (Z)-2-(3-bromo-α-t-butylhydrazonobenzyl)-3-hydroxypyridine 1-oxide (0.79 g) (compounds 29 and 28).
