chromium(VI) oxide in dimethyl sulfoxide T=25°C;

pyridine; thionyl chloride in liquid sulphur dioxide

1: 3-keto-2H,3H-1,2-benzisothiazole 1,1-dioxide / dichloromethane / |Reflux; |Inert atmosphere 2: cesium fluoride / N,N-dimethyl-formamide / 24 h / 140 °C / 760.05 Torr View Scheme