1: 1.) Br2, 2.) 1 N aq. NaHCO3 / 1.) CH2Cl2, -50 deg C to 0 deg C, 2.) r.t., 1 h 2: concd H2SO4 / Ambient temperature 3: 1 N aq. HCl, 38percent aq. CH2O / 1 h / Ambient temperature 4: DBU / diethyl ether View Scheme