1.1: potassium carbonate / ethyl acetate / 0.25 h / 25 - 30 °C 1.2: 2 h / 0 - 5 °C 2.1: 2,3-dicyano-5,6-dichloro-p-benzoquinone / dichloromethane / 0 - 30 °C View Scheme

sulfur T=180 - 185°C; 0.5 h;