1: 50 percent / Pyridine, CF3COOH, Dicyclohexylcarbodiimide / dimethylsulfoxide; benzene / 0.5 h / 50 °C 2: 85 percent / decahydronaphthalene / 2 h / 190 - 200 °C View Scheme

1: triethylamine / dichloromethane / 0.5 h / 20 °C 2: dichloromethane / 1 h 3: anhydrous xylene / 5 h / 138 °C / Inert atmosphere View Scheme

pyridine; dicyclohexyl-carbodiimide; trifluoroacetic acid in dimethyl sulfoxide; benzene T=50°C; 0.5 h;