Trityl chloride → 4-Bromo-1-trityl-1H-pyrazole

Participants

Reaction Steps

A suspension of 4-bromo-1H-pyrazole (10 g) in tetrahydrofuran (230 ml) was stirred for 1 hr at room temperature. While argon gas was provided, sodium hydride was slowly added at 0° C. to the suspension, followed by stirring for 30 min and then for an additional 30 min at room temperature. Then, trityl chloride (22.8 g) was slowly added at 0° C. to the suspension with stirring for 20 min. Further stirring was conducted for 3 hrs at room temperature before the reaction was terminated. Following the removal of excess sodium hydride with distilled water (3 ml) from the reaction at 0° C., the tetrahydrofuran solvent was evaporated in a vacuum and the concentrate thus obtained was diluted in ethyl acetate (200 ml) and washed with distilled water (200 ml) and then with brine (200 ml). The resulting organic layer was dried over anhydrous magnesium sulfate and concentrated by evaporation in vacuo. The residue was diluted in methylene chloride (2 ml) and recrystallized in methanol (200 ml) to give 4-bromo-1-trityl-1H-pyrazole (25 g).

Provenance & Evidence