Diisobutylaluminumhydride → (1-(2-chloro-5-fluoropyrimidin-4-yl)-3-methyl-1H-pyrazol-4-yl)methanol

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To a solution of ethyl 1-(2-chloro-5-fluoropyrimidin-4-yl)-3-methyl-1H-pyrazole-4-carboxylate 1 (4.9 g, 17.2 mmol) in 60 mL of anhydrous tetrahydrofuran (THF), was slowly added 38 mL (38 mmol) of 1M solution of di-isobutylaluminum hydride (DIBAL) in toluene with ice bath cooling. After being stirred for 2 hours at the same temperature, the reaction was quenched by slow addition of 1N-NaOH solution. It was diluted with ethyl acetate and washed with brine. The collected organic layer was dried over anhydrous sodium sulfate and then partially concentrated in vacou. To this, n-hexanes were added to form pale yellow precipitates. The resulting solids were collected by filtration and rinsed with n-hexanes and then dried with high vacuum to give 3.7 g (90%) of Intermediate No. 2; 1H NMR (300 MHz, CDCl3) δ 8.57 (1H, d, J=3.3 Hz), 8.52 (1H, s), 7.94 (1H, s), 4.72 (2H, s); MS (ESI) m/z 243 [M+H]+.

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