Cesium carbonate → 4-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole-1-propanenitrile

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Pyrazole-4-boronic acid pinacol ester (1 g, 1 equiv, 5.15 mmol) was dissolved in dimethylformamide (15 mL) followed by the addition of Cs2CO3 (0.86 g, 1.5 equiv, 7.73 mmol) and 3-chloropropionitrile (1.1 equiv, 5.67 mmol, 0.44 mL). The mixture was heated at 90° C. overnight. The reaction was diluted with ethyl acetate and washed with water (3×) and brine (3×). The organic phases was concentrated in vacuo onto silica gel and purified by flash chromatography (SiO2, CH2Cl2:CH3OH 100:0-90:10) to return the title compound (0.11 g, 9%). 1H NMR (500 MHz, DMSO): δ 1.26 (12H, s), 3.07 (2H, t), 4.40 (2H, t), 7.65 (1H, s), 8.04 (1H, s). MS m/z 248 (M+H+)+.

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