A mixture of 1-(5-chloro-2-thienyl)-2-(pyridin-4-yl)ethanone (0.68 mmol), secbutylhydrazin (1.37 mmol) and triethylamine (1.37 mmol) in 5 mL dichloromethane was refluxed for 2.5 h. The solvent was evaporated under reduced pressure and the residue was partitioned between ethyl acetate and water. The aqueous layer was extracted with ethyl acetate and the combined organic extracts were dried over MgSO4 filtered and concentrated. The residue was purified by chromatography on silica gel (dichloromethane:methanol 100:1 to 20:1) to afford 37 mg of 4-[1-sec-butyl-3-(5-chloro-2-thienyl)-1H-pyrazol-4-yl]pyridine (16% yield) and 48 mg of 4-[1-sec-butyl-5-(5-chloro-2-thienyl)-1H-pyrazol-4-yl]pyridine (21% yield).
