3,4-dihydro-2H-pyran → 4-bromo-6-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole

Participants

Reaction Steps

A mixture of 4-bromo-6-methyl-1H-indazole (1.05 g, 5 mmol), DHP (2.1 g, 25 mmol), and TsOH.H2O (96 mg, 0.5 mmol) in THF (50 ml) under nitrogen was heated at reflux overnight. The reaction mixture was concentrated in vacuo and to the residue was added DCM (300 mL) and water (50 mL). The organic layer was dried over MgSO4, filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography by using petroleum ether:EtOAc (100:1) as eluting solvents to afford 4-bromo-6-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole as light yellow oil (1.1 g, 90%) MS (ESI): m/z=295.1 [M+1]+.

Provenance & Evidence