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

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Reaction Conditions

Reaction Steps

A mixture of 3-bromo-7-trifluoromethyl-5-(4-trifluoromethyl-phenyl)-pyrazolo[1,5-a]pyrimidine (Example C.1 step 2a) (12.30 g, 30 mmol), trimethylsilylacetylene (8.3 mL, 60 mmol) and Et3N (6.3 mL, 45 mmol) in THF (30 mL) was stirred for 10 min at 23° C. while being purged with Argon, then PdCl2(PPh3)2 (105 mg, 0.5 mol %), PPh3 (20 mg, 0.25 mol %) and CuI (17 mg, 0.3 mol %) were added. Stirring was continued at 75° C. for 38 h. After 22 h, trimethylsilylacetylene (2.1 mL) and Et3N (2.1 mL) was added. Cooled to 23° C., diluted with ethyl acetate (100 mL), filtered through celite, washed with ethyl acetate. Removal of the solvent in vacuum left the 7-trifluoromethyl-5-(4-trifluoromethyl-phenyl)-3-trimethylsilanylethynyl-pyrazolo[1,5-a]-pyrimidine (13.65 g, 106%) as an orange solid, which can directly be used in the subsequent step. An analytical sample was obtained by silica gel column chromatography with heptane/EtOAc. MS (ISP) 427.0 [(M)+]; mp 136° C.

Provenance & Evidence