A vial containing 3-(4-bromo-benzyl)-2-ethyl-5,7-dimethyl-pyrazolo[1,5-a]pyrimidine (3) (10 g, 29.0 mmol), sodium azide (3.78 g, 58.1 mmol), copper(I) iodide (0.553 g, 2.90 mmol), N,N′-dimethylethylenediamine (0.469 ml, 4.36 mmol) and sodium ascorbate (0.288 g, 1.452 mmol) in ethanol (45 ml)/water (15.00 ml) was submitted to microwave irradiations for 1 h at 100° C. The reaction was diluted with EtOAc and washed with sat aqu Na2 CO3, water and brine. The organic layer was dried over anhydrous Na2 SO4, filtered and concentrated under HV. The crude product was purified by flash chromatography (silica gel, EtOAc/heptane 5% to 40%) to give a pale yellow solid.
