Br[C:2]1[C:7]([F:8])=[CH:6][C:5]([O:9][CH3:10])=[CH:4][C:3]=1[F:11].[Li]CCCC.[N:17]([C:26]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])=[N:18][C:19]([O:21][C:22]([CH3:25])([CH3:24])[CH3:23])=[O:20].N#N>C1COCC1>[F:11][C:3]1[CH:4]=[C:5]([O:9][CH3:10])[CH:6]=[C:7]([F:8])[C:2]=1[N:17]([C:26]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])[NH:18][C:19]([O:21][C:22]([CH3:23])([CH3:24])[CH3:25])=[O:20]In an oven-dried, N2-purged round bottom, 4-bromo-3,5-difluoroanisole (500 mg, 2.24 mmol) was dissolved in anhydrous THF (11 mL) and brought to −78° C. nBuLi (0.96 mL, 2.44 M in THF, 2.35 mmol) was added over 2 min. This was stirred for 5 min and then a solution di-tert-butyl azodicarboxylate (542 mg, 2.35 mmol) in anhydrous THF (3 mL) in an oven-dried, N2-purged pear flask was added in one portion via syringe. The reaction was removed from the ice bath and allowed to warm to room temperature over 30 min. The reaction, a clear solution, was quenched by the addition of aq. sat. NH4Cl. The material was extracted with two portions of ethyl acetate and the combined organics were dried over MgSO4 and concentrated in vacuo. Purification by silica gel flash chromatography (ethyl acetate in heptane) gave di-tert-butyl 1-(2,6-difluoro-4-methoxyphenyl)hydrazine-1,2-dicarboxylate (0.868 g, impure with ethyl acetate) as a clear oil. 1H NMR (400 MHz, CDCl3, δ): 6.48 (d, J=10.1 Hz, 2H) 3.73-3.85 (m, 3H) 1.36-1.60 (m, 18H).
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