1: phosphorus oxychloride, triethylamine / 1,2-dimethoxy-ethane / 1 h / 0 °C 2: methanol / Ambient temperature View Scheme

1: potassium tert-butoxide / 1,2-dimethoxy-ethane 2: phosphorus oxychloride, triethylamine / 1,2-dimethoxy-ethane / 1 h / 0 °C 3: methanol / Ambient temperature View Scheme

in methanol Ambient temperature;