Hydrazine hydrate (1:1) → (4-Tert-butoxy-3,6-difluoro-5-methoxypyridin-2-yl)hydrazine

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Reaction Steps

A mixture of 4-tert-butoxy-2,3,6-trifluoro-5-methoxypyridine (1.5 g. 6.4 mmol) and hydrazine monohydrate (1.7 mL, 34 mmol [Qun Li et al. J. Med. Chem. 1996, 39(16), 3070-3088]) in n-propanol (10 mL) was heated to reflux for 3 hours. The solvent was removed in vacuo and the residue was dissolved in dichlromethane, washed with water and concentrated to afford crude (4-tert-butoxy-3,6-difluoro-5-methoxypyridin-2-yl)hydrazine (1.4 g, 90%). 1.2 g of the material was redissolved in methanol (12 mL) and 20% aqueous sodium hydroxide (2.5 mL). Oxygen was passed through the solution with vigorous stirring for 20 hours. The deep blue solution was diluted with water (12 mL) and extracted with hexane (2×30 mL). The combined organics were washed with brine, dried over sodium sulfate and concentrated in vacuo. The residue was purified by column chromatography, eluting with ethyl acetate/hexane (1:16) to afford the title compound (0.9 g). 1H NMR (400 MHz, CDCl3) δ 7.74 (m, 1H), 3.93 (m, 3H), 1.41 (s, 9H). MSCI: m/z=218 (MH+).

Provenance & Evidence