3,4-dihydro-2H-pyran → 5-bromo-7-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-benzo[d]imidazole

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Reaction Steps

A mixture of 74 (1.09 g, 5.19 mmol), TsOH.H2O (98 mg, 0.51 mmol), 3,4-dihydro-2H-pyran (2.4 mL, 26 mmol) in THF (15 mL) was degassed and then heated to reflux overnight. The solvent was removed in vacuo. The residue was partitioned between with DCM (300 mL) and water (50 mL). The organic layer was separated, dried (MgSO4), filtered and concentrated. The crude product was purified by SiO2 chromatography eluting with a MeOH/DCM gradient (0.5% to 1% MeOH) to afford 1.45 g (95%) of 5-bromo-7-methyl-1-(tetrahydro-2H-pyran-2-yl)-1H-benzo[d]imidazole (76) as yellow solid: MS (ESI) m/z=295.1 [M+1]+.

Provenance & Evidence