4-(N,N-dimethlyamino)pyridine; dicyclohexyl-carbodiimide in tetrahydrofuran T=20°C; 25.5 h; Cooling with ice;

1: 54 percent / potassium iodide, potassium hydroxide / ethanol; H2O / 20 h / Heating 2: 67 percent / hydroquinone, p-toluenesulphonic acid / benzene / 20 h / Heating 3: 1.) thionyl chloride, 2,6-di-tert-butyl-4-methyl phenol, DMF; 2.) triethylamine / 1.) 25 min; 2.) chloroform, room t., 24 h View Scheme

1: 67 percent / hydroquinone, p-toluenesulphonic acid / benzene / 20 h / Heating 2: 1.) thionyl chloride, 2,6-di-tert-butyl-4-methyl phenol, DMF; 2.) triethylamine / 1.) 25 min; 2.) chloroform, room t., 24 h View Scheme

1: 54 percent / potassium iodide, potassium hydroxide / ethanol; H2O / 20 h / Heating 2: 67 percent / hydroquinone, p-toluenesulphonic acid / benzene / 20 h / Heating 3: 1.) thionyl chloride, 2,6-di-tert-butyl-4-methyl phenol, DMF; 2.) triethylamine / 1.) 25 min; 2.) chloroform, room t., 24 h View Scheme