Potassium Carbonate → 3-cyclopropyl-1-((6-methylpyridin-2-yl)methyl)-4-nitro-1H-indazole

Participants

Reaction Conditions

Reaction Steps

A 250 mL round bottom flask was charged with 1,4-dioxane/H2O (150 mL/30 mL). The flask was cooled to 0° C. and vacuum was applied for 20 minutes. A 500 mL round bottom flask was charged with cyclopropylboronic acid (Preparation C, 15.90 g, 185.1 mmol), 3-bromo-1-((6-methylpyridin-2-yl)methyl)-4-nitro-1H-indazole (Preparation C, 25.71 g, 74.06 mmol), K2CO3 (40.94 g, 296.2 mmol), palladium acetate (0.4988 g, 2.222 mmol) and sodium 2′-(dicyclohexylphosphino)-2,6-dimethoxybiphenyl-3-sulfonate (2.278 g, 4.443 mmol). The flask was evacuated and back filled with nitrogen three times. The cold degassed dioxane/H2O mixture was added to the 500 mL flask, which was evacuated and back filled with argon 5 times. The reaction mixture was heated at reflux for 5 hours under argon. The reaction mixture was cooled to ambient temperature, filtered through a pad of Celite, and the filter pad was washed with H2O (100 mL) and EtOAc (300 mL). The aqueous layer with extracted with EtOAc. The combined organic phases were dried (Na2SO4) and concentrated under reduced pressure. The resulting solid was dissolved in DCM and washed with saturated NaHCO3 aqueous solution. The organic phase was dried (Na2SO4) and concentrated under reduced pressure to give a dark colored residue, which was dissolved in DCM (30 mL) and silica gel (50 g) was added. The DCM was removed under reduced pressure. The crude product absorbed by silica gel was loaded onto a column of silica gel and the column was eluted with EtOAc/hexanes (1:1). The fractions containing product were concentrated under reduced pressure to provide the product (22.1 g).

Provenance & Evidence