1: 89 percent / acetic acid; H2O / 5 h / Ambient temperature 2: 1.) dibutyltin oxide, 2.) Br2, tributyltin methoxide / 1.) 0 deg C, 2.) CH2Cl2 3: aq. H2SO4 / 3.25 h / 60 °C 4: sodium cyanoborohydride / methanol / 336 h / in a refrigerator 5: 49 percent / H2, HCl / Pd(OH)2 on carbon / methanol / 5 h / 760 Torr View Scheme