in diethyl ether stirring, warming from -78°C to ambient temp.; cooling to -30°C yields one enantiomer (filtn., drying in vacuo), cooling to -78°C or evaporation of mother liquor yields mixtures of enantiomers, which could be sepd. by repeated recrystn. from hexane and/or diethyl ether; elem. anal.;

in diethyl ether stirring, warming from -78°C to ambient temp.; cooling to -30°C yields one enantiomer (filtn., drying in vacuo), cooling to -78°C or evaporation of mother liquor yields mixtures of enantiomers, which could be sepd. by repeated recrystn. from hexane and/or diethyl ether; elem. anal.;