1: 1.) 1,1'-carbonyldiimidazole / 1.) DMF, 40 deg C, 30 min, 2.) 20 deg C, 11 h 2: methanolic NaOH 3: Et3N / tetrahydrofuran; CH2Cl2 / 0.17 h / 0 °C 4: LiCl / dimethylformamide / 0.08 h / 110 °C 5: HBr/AcOH / 4 h / 20 °C 6: methanol / 24 h / 20 °C View Scheme