n-BuLi in dichloromethane under N2 or Ar; n-BuLi in hexane added (-80°C) to alkyne in THF; stirred (-100°C, 20 min); Cr complex in THF added; stirred (ambient temp., 30 min); solvent removed; dissolved in CH2Cl2; treated with Et3OBF4 (0°C); stirred (60 min); filtered at -20°C through silica layer using CH2Cl2 as eluent; solvent evapd.; sepd. by chromy. (silica, -20°C, pentane-CH2Cl2 2:1, 1:1 to 1:3, 1:4); elem. anal.;
n-BuLi in dichloromethane under N2 or Ar; n-BuLi in hexane added (-80°C) to alkyne in THF; stirred (-100°C, 20 min); W complex in THF added; stirred (ambient temp., 30 min); solvent removed; dissolved in CH2Cl2; treated with Et3OBF4 (0°C); stirred (60 min); filtered at -20°C through silica layer using CH2Cl2 as eluent; solvent evapd.; sepd. by chromy. (silica, -20°C, pentane-CH2Cl2 2:1, 1:1 to 1:3, 1:4); elem. anal.;
