1: 74 percent / acetonitrile 2: 1) NBS; 2) 0.5 N HCl, NaOH / 1) THF, -78 deg C; 2) MeOH, 20 min 3: -78 °C 4: 2) NaOAc / 1) from -78 deg C to RT; 2) water, 15 h, reflux View Scheme

Multi-step reaction with 3 steps 1: acetonitrile / 12 h / 23 °C2: N-bromosuccinimide / tetrahydrofuran / a.) -78 deg C, 4 h, b.) to room temperature3: 0.5M HCl / methanol / 0.33 h / Ambient temperature