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