1: 1.) dihydropyran, p-toluenesulfonic acid, 2.) triphenylphosphine dibromide / 1.) ether, 2.) CH2Cl2, 0 deg C 2: 1.) n-BuLi / 1.) THF, hexane, -60 deg C, 10 min, 2.) 2 h, RT 3: 93 percent / 6percent sodium amalgam, Na2HPO4 / tetrahydrofuran; methanol / 5 h View Scheme