Triethylamine → 5-(4-Chloro-3-methyl-phenyl)-7-trifluoromethyl-3-trimethylsilanylethynyl-pyrazolo[1,5-a]pyrimidine

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Reaction Steps

A mixture of 5-(4-chloro-3-methyl-phenyl)-3-iodo-7-trifluoromethyl-pyrazolo[1,5-a]pyrimidine (5.85 g, 12.4 mmol), trimethylsilylacetylene (3.33 mL, 24.1 mmol) and triethylamine (3.71 mL, 26.7 mmol) in N,N-dimethylformamide (20 mL) was stirred for 10 min at room temperature while being purged with Argon, then PdCl2(PPh3)2 (94 mg, 1 mol %), PPh3 (35 mg, 1 mol %) and CuI (8 mg, 0.3 mol %) were added. Stirring was continued at 90° C. for 4 h. The reaction mixture was cooled to room temperature, diluted with ethyl acetate (150 mL), washed with water (2×50 mL) and brine (70 mL), dried (MgSO4) and evaporated to give 5-(4-chloro-3-methyl-phenyl)-7-trifluoromethyl-3-trimethylsilanylethynyl-pyrazolo[1,5-a]pyrimidine (5.79 g, 106%) as an orange solid, which was dissolved in THF (70 mL) and MeOH (70 mL), while stirring at 0° C. potassium carbonate (196 mg, 1.42 mmol) was added and the mixture was stirred at 0° C. for 5 h. The mixture was diluted with ice water (250 mL) and extracted with TBME (3×250 mL). The combined organic layers were washed with brine (300 mL), dried (MgSO4) and evaporated. The crude product was further purified by column chromatography on silica gel (heptane/EtOAc 9:1) followed by trituration with heptane to give 5-(4-chloro-3-methyl-phenyl)-3-ethynyl-7-trifluoromethyl-pyrazolo[1,5-a]pyrimidine (3.22 g, 68%) as an orange solid. MS (EI) 335.0 [(M+H)+]; mp 166° C.

Provenance & Evidence