Short-RInChIKey=SA-FUHFF-UHFFFADPSC-VJXASIWJXV-UHFFFADPSC-NUHFF-NCPJL-NUHFF-ZZZ

5-[(~{E})-(Diisopropylamino)azo]-1~{H}-pyrazole-4-carboxylic acid ethyl ester (500 mg, 1.87 mmol, 1.00 equiv) was dissolved in DMSO (19.0 mL) and cesium carbonate (731 mg, 2.24 mmol, 1.20 equiv) was added. The reaction mixture was cooled to 0 °C and 1-bromo-4-(bromomethyl)benzene (935 mg, 3.74 mmol, 2.00 equiv) was slowly added. After the addition, the reaction mixture was slowly warmed to 21 °C and stirred for 16 hours at this temperature. For work-up, ice water was added to the reaction mixture. The aqueous phase was extracted three times with ethyl acetate and the combined organic phase was washed with water and brine, dried over Na2SO4 and filtered.