Potassium Carbonate → 6-Chloro-5-(4-methoxyphenyl)-1H-indazole-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-bromo-6-chloro-1H-indazole-3-carboxylic acid (2.0 g, 7.3 mmol), 4-methoxyphenyl boronic acid (1.13 g, 7.40 mmol) in EtOH (50 mL) and toluene (50 mL) was added 2N aqueous potassium carbonate solution (21.8 mL, 43.6 mmol). The reaction mixture was degassed with N2 for 5 minutes, treated with [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (296 mg, 0.36 mmol) and degassed with N2 for an additional 5 minutes. The reaction mixture was sealed in a pressure tube and heated to 130° C. for 3 hours. As the reaction progressed, the suspension became clear and turned to orange then dark brown. The reaction mixture was cooled to room temperature, and filtered through Celite®. The filtrate was concentrated in vacuo and the residue was partitioned between EtOAc (150 mL) and water (150 mL). The aqueous layer was acidified to pH 2, and extracted with EtOAc. Silicycle-thiol resin was added to the organic layer and the suspension was stirred for 10 minutes. The suspension was filtered and activated charcoal was added to the filtrate. The suspension was stirred at room temperature for another 20 minutes and filtered. The resulting light yellow solution was concentrated in vacuo and the residue was triturated with CH2Cl2 and MeCN. The solid was filtered to provide the title compound (280 mg, 13% yield) as a light yellow solid. The filtrate was concentrated, diluted with EtOAc (20 mL) and filtered to give another batch of desired product (80 mg). MS (ES+) 303.2 (M+H)+. 1H NMR (500 MHz, DMSO-d6) δ 7.98 (s, 1H), 7.86 (s, 1H), 7.38 (d, J=8.29 Hz, 2H), 7.03 (d, J=8.78 Hz, 2H), 3.82 (s, 3H).

Provenance & Evidence