Lithium Hexamethyldisilazide → 2,6-Difluoro-N-{1-[(2-methyl-4-nitrophenyl)methyl]-1H-pyrazol-3-yl}benzamide

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Reaction Steps

To a solution of 2,6-difluoro-N-(1H-pyrazol-3-yl)benzamide (for a preparation see Intermediate 9)(1.5 g, 6.72 mmol) in THF (30 ml) at ambient temperature under nitrogen was added 1.0 M lithium bis(trimethylsilyl)amide in THF (6.5 ml, 6.50 mmol, Aldrich). The solution was stirred for 30 min. To the solution was added a solution of 1-(bromomethyl)-2-methyl-4-nitrobenzene (1.5 g, 6.52 mmol) in THF (20 ml). The resulting pale orange solution was stirred at ambient temperature under nitrogen over the weekend. The solvent was evaporated in vacuo and the residue partitioned between ethyl acetate (150 ml) and saturated aqueous sodium hydrogen carbonate (50 ml). The phases were separated and the aqueous layer washed with ethyl acetate (25 ml). The combined organic phases were dried (MgSO4), filtered and the solvent removed in vacuo to leave a yellow oil (2.87 g). The sample was loaded in dichloromethane and purified on silica 100 g using 0-100% ethyl acetate-cyclohexane. The appropriate fractions were combined and evaporated in vacuo to give the title compound as a white foam (1.6 g); LCMS: (System 4) MH+=373, tRET=2.65 min.

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