Ethanol → 7-Trifluoromethyl-5-(4-trifluoromethyl-phenyl)-pyrazolo[1,5-a]pyridine-3-carboxylic acid ethyl ester

Participants

Reaction Steps

A solution of 1-amino-6-trifluoromethyl-4-(4-trifluoromethyl-phenyl)-1H-pyridine-2-thione (example C.22 step 6) (3.14 g, 9.28 mmol) and 2-chloro-3-oxo-propionic acid ethyl ester (example C.22 reagent 1) (4.19 g, 27.85 mmol) in EtOH (45 mL) was refluxed for 20 h, the added again 2-chloro-3-oxo-propionic acid ethyl ester (example C.22 reagent 1) (2.20 g, 14.61 mmol) and refluxing was continued for another 18 h. Poured into sat. NaHCO3-sol., extracted with EtOAc, washed the organic layer with brine, dried over Na2SO4 and evaporated to leave a residue, which was purified by flash chromatography (600 g SiO2) with heptane/EtOAc 9:1, followed by trituration with heptane (ca. 50 mL) at −70° C. to give the title compound as a light yellow solid (2.30 g, 62%). MS (ISP) 403 [(M+H)+]; mp 130° C.

Provenance & Evidence