Trityl chloride → 3-Bromo-4-fluoro-1-trityl-1H-indazole-5-carboxylic Acid Methyl Ester

Participants

Reaction Steps

Under ice-cooling, to a solution of 2.99 g of 3-bromo-4-fluoro-1H-5-indazolecarboxylic acid methyl ester obtained in Production Example II-13-d in 30 ml tetrahydrofuran was added 526 mg of 60% sodium hydride, and the mixture was stirred for 25 minutes. Then, 3.21 g of triphenylmethyl chloride was added and the mixture was stirred at the same temperature for 15 minutes and further stirred at room temperature for 45 minutes. The reaction mixture was ice-cooled again, saturated aqueous sodium hydrogencarbonate solution was added and the mixture was extracted with 100 ml of ethyl acetate. The organic layer was sequentially washed with water (×2) and brine, dried over anhydrous magnesium sulfate and the solvent was evaporated. The crude product was purified and separated by silica gel column chromatography (ethyl acetate:hexane=1:9), and the resulting crystals were recrystallized from diisopropyl ether, to give 1.73 g of the title compound as white needles.

Provenance & Evidence