Pivalic acid → 5-(5-chloro-2-difluoromethoxyphenyl)-4-nitro-1-(2-trimethylsilanylethoxymethyl)-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-nitro-1-(2-trimethylsilanylethoxymethyl)-1H-pyrazole (preparation described in WO2011003065) (46.5 g, 191 mmol) in DMA (350 mL) was added 2-bromo-4-chloro-1-difluoromethoxybenzene (64.0 g, 248 mmol), palladium (II) acetate (2.15 g, 9.6 mmol), di-(adamantyl)-n-butylphosphine (5.0 g, 13.4 mmol), potassium carbonate (79.2 g, 573 mmol) and trimethylacetic acid (5.27 g, 51.6 mmol). The mixture was degassed with nitrogen for 10 minutes then heated at 130° C. for 8 hours. The reaction mixture was allowed to cool to room temperature, diluted with ethyl acetate and washed with water and brine, dried (MgSO4), filtered and evaporated. The resultant crude material was purified by flash chromatography on silica eluting with 0-10% EtOAc in cyclohexane to afford 5-(5-chloro-2-difluoromethoxyphenyl)-4-nitro-1-(2-trimethylsilanylethoxymethyl)-1H-pyrazole (62.4 g, 78%). 1H NMR (400 MHz, CDCl3) δ: (ppm) 8.24 (s, 1H), 7.52-7.53 (m, 2H), 6.39 (t, 1H), 5.29-5.30 (m, 2H), 3.63-3.64 (m, 2H), 0.90 (s, 9H).

Provenance & Evidence