1.1: triethylamine / dichloromethane; toluene / 2.17 h / 0 - 30 °C 2.1: 4-(N,N-dimethlyamino)pyridine / toluene / 0.08 h / 18 - 20 °C 2.2: 19 h / 25 - 30 °C 3.1: sulfuric acid / water; tetrahydrofuran / 20 h / 0 - 35 °C View Scheme