反应详情

A solution of 5-bromovaleryl chloride (2.1 mL, 15.7 mmol) in dry dimethylacetamide (DMA) (35 mL) was cooled to −10° C. (ice water bath) under N2; a solution of 5-(4-methoxy-phenyl)-1H-pyrazol-3-ylamine (3.0 g, 15.7 mmol) and diisopropylethylamine (2.74 mL, 15.7 mmol) in dry DMA (15 mL) was added over 30 min. After two hours at −10° C., LCMS shows completion of the reaction (acylation on the pyrazole ring was also detected). The reaction was quenched by addition of H2O (ca. 50 mL), and the thick white precipitate formed upon addition of water is recovered by filtration. When the reaction was allowed to reach room temperature before quenching, a putative exchange of Br with Cl caused reactivity problems in subsequent steps. Washing with Et2O (3×10 mL) efficiently removed the byproduct (acylation on pyrazole ring). 4.68 g of the title compound was obtained as a white powder (13.3 mmol, 85% yield). Mp=149.5-151.5° C.

1. customcompletion of the reaction (acylation on the pyrazole ring
2. customThe reaction was quenched by addition of H2O (ca. 50 mL)
3. customthe thick white precipitate formed upon addition of water
4. filtrationis recovered by filtration
5. customto reach room temperature
6. custombefore quenching
7. washWashing with Et2O (3×10 mL)
8. customefficiently removed the byproduct (acylation on pyrazole ring)