1: 89 percent / 1N HCl / CH2Cl2; diethyl ether / 1 h / Ambient temperature 2: 53 percent / tetrahydrofuran / 120 h / Ambient temperature 3: 1a.) 1N aq. NaOH, 1b.) 1N HCl, 2.) HBr, HOAc / 1a.) THF, RT, 30 min, 2.) RT, 2.5 h 4: NaHCO3, NaOH / tetrahydrofuran; H2O / 24 h / Ambient temperature View Scheme