1-(Tetrahydro-2H-pyran-2-yl)-1H-pyrazole

110-87-2

288-13-1

449758-17-2

General procedure for the synthesis of 1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazole from 3,4-dihydro-2H-pyran and pyrazole: cf. Example 1 [1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-5-yl]boronic acid. Pyrazole (14.3 g, 0.21 mol) was mixed with 3,4-dihydro-2H-pyran (29 mL, 0.32 mol) and trifluoroacetic acid (0.1 mL, 0.0013 mol) and heated under reflux conditions for 5 hours. Upon completion of the reaction, the mixture was cooled to room temperature, followed by the addition of sodium hydride (60% dispersed in mineral oil, 0.2 g, 0.008 mol) and stirred for 10 min. Finally, the reaction mixture was purified by reduced pressure distillation (60-65 °C, 0.5-1 mmHg) to afford the target product 1-(tetrahydropyran-2-yl)-1H-pyrazole (30.8 g, 96% yield).