in tetrahydrofuran byproducts: graphite, KCl; (argon); stirring (-78°C, 1 h), warming to room temp.; filtration, evapn., chromy. (SiO2; n-hexane and n-hexane/toluene); elem.anal.;

in tetrahydrofuran byproducts: KCl; (argon); -78 to -30°C, stirring (1 h), warming to room temp., stirring (1 h); filtration, solvent removal (vac.), addn. of toluene, filtration, solvent removal (vac.), addn. of CH2Cl2 and SiO2, drying (vac.), chromy. (SiO2; n-hexane and n-hexane/toluene), recrystn. (toluene); elem. anal.;

in tetrahydrofuran byproducts: KCl; (argon); -78 to -30°C, stirring (1 h), slow warming to room temp.; filtration, solvent removal (vac.), addn. of toluene, filtration, solvent removal (vac.), addn. of CH2Cl2 and SiO2, drying (vac.), chromy. (SiO2; n-hexane and n-hexane/toluene), recrystn. (toluene); elem. anal.;