p-Toluenesulfonic acid → 5-Nitro-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole

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Reaction Steps

To a solution of 5-nitroindazole (20.0 g, 123 mmol) in methylene chloride (400 ml) were added 3,4-dihydro-2H-pyran (16.8 ml, 184 mmol) and p-toluenesulfonic acid (4.22 g, 24.5 mmol) at room temperature, and stirred for 2 hours. After the reaction solution was concentrated, a saturated aqueous sodium hydrogencarbonate solution was added thereto, followed by extraction with chloroform. The organic layer was dried over anhydrous magnesium sulfate and distilled under reduced pressure to remove the solvent, and resulting residue was purified by a silica gel column chromatography (eluent: hexane/ethyl acetate=5/1) to obtain 5-nitro-1-tetrahydro-2H-pyran-2-yl-1H-indazole (26.6 g, 88%).

Provenance & Evidence