Cyclopropylboronic acid → 3-cyclopropyl-1-((1-ethyl-1H-pyrazol-3-yl)methyl)-4-nitro-1H-indazole

Participants

Reaction Conditions

Reaction Steps

A 100 mL flask was charged with 1,4-dioxane/H2O (50 mL/10 mL). The flask was cooled to 0° C. under vacuum for 20 minutes. A 250 mL round bottom flask was charged with cyclopropylboronic acid (5.22 g, 60.8 mmol), 3-bromo-1-((1-ethyl-1H-pyrazol-3-yl)methyl)-4-nitro-1H-indazole (8.51 g, 24.3 mmol), palladium diacetate (0.218 g, 0.972 mmol) and sodium 2′-(dicyclohexylphosphino)-2,6-dimethoxybiphenyl-3-sulfonate (0.997 g, 1.94 mmol). The flask was evacuated and back filled with N2 (repeated 3 times). The cold degassed dioxane/H2O mixture was added to the 250 mL flask, which was evacuated and back filled with argon (repeated 5 times). The reaction mixture was heated to 100° C. for 6 hours. The mixture was cooled to ambient temperature, filtered through a pad of Celite, and the filter pad was washed with H2O and EtOAc. The aqueous layer was extracted with EtOAc. The combined organic phases were dried (Na2SO4) and concentrated under reduced pressure to give a dark colored residue, which was dissolved in DCM (20 mL) and silica gel (20 g) was added. DCM was removed under reduced pressure. The crude product absorbed by silica gel was loaded onto a short pad of silica gel and eluted with EtOAc/hexanes (1:1). The desired fractions were concentrated under reduced pressure to give the product (7.55 g).

Provenance & Evidence