n-butyllithium; N,N,N',N,-tetramethylethylenediamine in tetrahydrofuran; hexane to a stirred THF soln. of the furan and TMEDA n-BuLi in hexane added dropwise (-78°C), stirred (2 h, -40 to -20°C), cooled (-78°C), Bu3SnCl added dropwise (30 min), warmed (room temp.), stirred overnight; quenched (cold water), extracted (ether), washed (satd. NaHCO3), dried (MgSO4), concentrated (vac.), residue passed through a short alumina plug (hexane), solvent removed;