For the final oxidation to target compound 3b, we developed a protocol based on a work using silica-supported CAN for the synthesis of benzoquinones. Beside other advantages, silica-supported CAN can be easily removed by filtration after the reaction. Furthermore, it allows for using CH 2 Cl 2 as the solvent, which dissolves 2b better than the usual aqueous acetonitrile. The reaction was carried out simply by adding CH 2 Cl 2 and 2b to freshly prepared silica-supported CAN and stirring for 1 h at room temperature. Facile work-up afforded crude 3b in quantitative yields. For removing impurities, the solid was recrystallized from 1,4dioxane, which reduced the yield to 64%. Despite the loss during recrystallization, this is still significantly higher than reported before without experimental details.