反应详情

To a solution of 128 (22 g, 0.095 mol) in dry THF (660 mL) was added 3,4-dihydro-2H-pyran (24 g, 0.286 mol) and camphorsulfonic acid (2.2 g, 0.00948 mol) and the solution was heated to reflux for 16 h. The resulting mixture was concentrated, and the residue obtained was purified by SiO2 chromatography eluting with 20% EtOAc/petroleum ether to afford 27 g (90%) of 5-bromo-4-chloro-1-(tetrahydro-pyran-2-yl)-1H-benzoimidazole (130) as pale yellow solid.

1. temperaturethe solution was heated
2. temperatureto reflux for 16 h
3. concentrationThe resulting mixture was concentrated
4. customthe residue obtained
5. customwas purified by SiO2 chromatography
6. washeluting with 20% EtOAc/petroleum ether