1: 88 percent / trifluoroacetic acid, 1,3-dicyclohexylcarbodiimide / benzene; pyridine; dimethylsulfoxide / 18 h 2: 1.) n-BuLi; 2.) CuI-Bu3P, and Bu3P / 1.) THF, -78 deg C, 20 min, 30 min; 2.) THF, ether, -78 deg C 10 min, - 30 deg C 1 h; 3.) THF, ether, HMPA, -30 deg C, 3 h 3: 78 percent / pyridine, 50percent aq. HF / 1.) 0 deg C, 30 min; 2.) rt, 4.5 h 4: aluminum amalgam / tetrahydrofuran; H2O / addition in equal portion after 10 h, 17 h and 23h; rt 15 h View Scheme

1: 88 percent / trifluoroacetic acid, 1,3-dicyclohexylcarbodiimide / benzene; pyridine; dimethylsulfoxide / 18 h 2: 1.) n-BuLi, triphenylmethane / 1.) hexane-THF, 0 deg C, 15 min; 2.) hexane-THF, -78 deg C,15 min 3: 97 percent / silica gel / toluene / 9 h / Heating View Scheme

1: 88 percent / trifluoroacetic acid, 1,3-dicyclohexylcarbodiimide / benzene; pyridine; dimethylsulfoxide / 18 h 2: 1.) n-BuLi, triphenylmethane / 1.) hexane-THF, 0 deg C, 15 min; 2.) hexane-THF, -78 deg C,15 min 3: 98 percent / silica gel / toluene / 9 h / Heating View Scheme