1.1: selenium(IV) oxide / 1,4-dioxane / 4 h / Inert atmosphere; Reflux 2.1: pyridinium p-toluenesulfonate / dichloromethane / 2 h / 0 - 20 °C / Inert atmosphere 3.1: diisobutylaluminium hydride / dichloromethane / 1 h / -10 - 20 °C / Cooling with ice 4.1: oxalyl dichloride; dimethyl sulfoxide / dichloromethane / 1 h / Inert atmosphere 4.2: 1.5 h / -78 - 20 °C / Inert atmosphere 5.1: toluene-4-sulfonic acid / methanol / 2 h / 0 - 20 °C View Scheme

N-bromosuccinmide in tetrachloromethane 5 h; Heating;

selenium(IV) oxide in 1,4-dioxane 4 h; Inert atmosphereReflux; regioselective reaction;